lodash v4.2.1
_.chunk
_.compact
_.concat
_.difference
_.differenceBy
_.differenceWith
_.drop
_.dropRight
_.dropRightWhile
_.dropWhile
_.fill
_.findIndex
_.findLastIndex
_.first
->head
_.flatten
_.flattenDeep
_.fromPairs
_.head
_.indexOf
_.initial
_.intersection
_.intersectionBy
_.intersectionWith
_.join
_.last
_.lastIndexOf
_.pull
_.pullAll
_.pullAllBy
_.pullAt
_.remove
_.reverse
_.slice
_.sortedIndex
_.sortedIndexBy
_.sortedIndexOf
_.sortedLastIndex
_.sortedLastIndexBy
_.sortedLastIndexOf
_.sortedUniq
_.sortedUniqBy
_.tail
_.take
_.takeRight
_.takeRightWhile
_.takeWhile
_.union
_.unionBy
_.unionWith
_.uniq
_.uniqBy
_.uniqWith
_.unzip
_.unzipWith
_.without
_.xor
_.xorBy
_.xorWith
_.zip
_.zipObject
_.zipObjectDeep
_.zipWith
_.countBy
_.each
->forEach
_.eachRight
->forEachRight
_.every
_.filter
_.find
_.findLast
_.flatMap
_.forEach
_.forEachRight
_.groupBy
_.includes
_.invokeMap
_.keyBy
_.map
_.orderBy
_.partition
_.reduce
_.reduceRight
_.reject
_.sample
_.sampleSize
_.shuffle
_.size
_.some
_.sortBy
_.after
_.ary
_.before
_.bind
_.bindKey
_.curry
_.curryRight
_.debounce
_.defer
_.delay
_.flip
_.memoize
_.negate
_.once
_.overArgs
_.partial
_.partialRight
_.rearg
_.rest
_.spread
_.throttle
_.unary
_.wrap
_.clone
_.cloneDeep
_.cloneDeepWith
_.cloneWith
_.eq
_.gt
_.gte
_.isArguments
_.isArray
_.isArrayLike
_.isArrayLikeObject
_.isBoolean
_.isDate
_.isElement
_.isEmpty
_.isEqual
_.isEqualWith
_.isError
_.isFinite
_.isFunction
_.isInteger
_.isLength
_.isMatch
_.isMatchWith
_.isNaN
_.isNative
_.isNil
_.isNull
_.isNumber
_.isObject
_.isObjectLike
_.isPlainObject
_.isRegExp
_.isSafeInteger
_.isString
_.isSymbol
_.isTypedArray
_.isUndefined
_.lt
_.lte
_.toArray
_.toInteger
_.toLength
_.toNumber
_.toPlainObject
_.toSafeInteger
_.toString
_.assign
_.assignIn
_.assignInWith
_.assignWith
_.at
_.create
_.defaults
_.defaultsDeep
_.extend
->assignIn
_.extendWith
->assignInWith
_.findKey
_.findLastKey
_.forIn
_.forInRight
_.forOwn
_.forOwnRight
_.functions
_.functionsIn
_.get
_.has
_.hasIn
_.invert
_.invertBy
_.invoke
_.keys
_.keysIn
_.mapKeys
_.mapValues
_.merge
_.mergeWith
_.omit
_.omitBy
_.pick
_.pickBy
_.result
_.set
_.setWith
_.toPairs
_.toPairsIn
_.transform
_.unset
_.values
_.valuesIn
_
_.chain
_.tap
_.thru
_.prototype[Symbol.iterator]
_.prototype.at
_.prototype.chain
_.prototype.commit
_.prototype.flatMap
_.prototype.next
_.prototype.plant
_.prototype.reverse
_.prototype.toJSON
->value
_.prototype.value
_.prototype.valueOf
->value
_.camelCase
_.capitalize
_.deburr
_.endsWith
_.escape
_.escapeRegExp
_.kebabCase
_.lowerCase
_.lowerFirst
_.pad
_.padEnd
_.padStart
_.parseInt
_.repeat
_.replace
_.snakeCase
_.split
_.startCase
_.startsWith
_.template
_.toLower
_.toUpper
_.trim
_.trimEnd
_.trimStart
_.truncate
_.unescape
_.upperCase
_.upperFirst
_.words
_.attempt
_.bindAll
_.cond
_.conforms
_.constant
_.flow
_.flowRight
_.identity
_.iteratee
_.matches
_.matchesProperty
_.method
_.methodOf
_.mixin
_.noConflict
_.noop
_.nthArg
_.over
_.overEvery
_.overSome
_.property
_.propertyOf
_.range
_.rangeRight
_.runInContext
_.times
_.toPath
_.uniqueId
_.VERSION
_.templateSettings
_.templateSettings.escape
_.templateSettings.evaluate
_.templateSettings.imports
_.templateSettings.interpolate
_.templateSettings.variable
Creates an array of elements split into groups the length of size
.
If array
can't be split evenly, the final chunk will be the remaining
elements.
[size=0]
(number): The length of each chunk.array
(Array): The array to process.
(Array): Returns the new array containing chunks.
_.chunk(2, ['a', 'b', 'c', 'd']);
// => [['a', 'b'], ['c', 'd']]
_.chunk(3, ['a', 'b', 'c', 'd']);
// => [['a', 'b', 'c'], ['d']]
Creates an array with all falsey values removed. The values false
, null
,
0
, ""
, undefined
, and NaN
are falsey.
array
(Array): The array to compact.
(Array): Returns the new array of filtered values.
_.compact([0, 1, false, 2, '', 3]);
// => [1, 2, 3]
Creates a new array concatenating array
with any additional arrays
and/or values.
array
(Array): The array to concatenate.[values]
(...*): The values to concatenate.
(Array): Returns the new concatenated array.
var array = [1];
var other = _.concat(array, 2, [3], [[4]]);
console.log(other);
// => [1, 2, 3, [4]]
console.log(array);
// => [1]
Creates an array of unique array
values not included in the other
provided arrays using SameValueZero
for equality comparisons.
array
(Array): The array to inspect.[values]
(...Array): The values to exclude.
(Array): Returns the new array of filtered values.
_.difference([3, 2, 1], [4, 2]);
// => [3, 1]
This method is like _.difference
except that it accepts iteratee
which
is invoked for each element of array
and values
to generate the criterion
by which uniqueness is computed. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.[values]
(...Array): The values to exclude.array
(Array): The array to inspect.
(Array): Returns the new array of filtered values.
_.differenceBy(Math.floor, [4.4, 2.5], [3.1, 2.2, 1.3]);
// => [3.1, 1.3]
// The `_.property` iteratee shorthand.
_.differenceBy('x', [{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }]);
// => [{ 'x': 2 }]
This method is like _.difference
except that it accepts comparator
which is invoked to compare elements of array
to values
. The comparator
is invoked with two arguments: (arrVal, othVal).
[comparator]
(Function): The comparator invoked per element.[values]
(...Array): The values to exclude.array
(Array): The array to inspect.
(Array): Returns the new array of filtered values.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
_.differenceWith(_.isEqual, [{ 'x': 1, 'y': 2 }], objects);
// => [{ 'x': 2, 'y': 1 }]
Creates a slice of array
with n
elements dropped from the beginning.
[n=1]
(number): The number of elements to drop.array
(Array): The array to query.
(Array): Returns the slice of array
.
_.drop([1, 2, 3]);
// => [2, 3]
_.drop(2, [1, 2, 3]);
// => [3]
_.drop(5, [1, 2, 3]);
// => []
_.drop(0, [1, 2, 3]);
// => [1, 2, 3]
Creates a slice of array
with n
elements dropped from the end.
[n=1]
(number): The number of elements to drop.array
(Array): The array to query.
(Array): Returns the slice of array
.
_.dropRight([1, 2, 3]);
// => [1, 2]
_.dropRight(2, [1, 2, 3]);
// => [1]
_.dropRight(5, [1, 2, 3]);
// => []
_.dropRight(0, [1, 2, 3]);
// => [1, 2, 3]
Creates a slice of array
excluding elements dropped from the end.
Elements are dropped until predicate
returns falsey. The predicate is
invoked with three arguments: (value, index, array).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.array
(Array): The array to query.
(Array): Returns the slice of array
.
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.dropRightWhile(function(o) { return !o.active; }, users);
// => objects for ['barney']
// The `_.matches` iteratee shorthand.
_.dropRightWhile({ 'user': 'pebbles', 'active': false }, users);
// => objects for ['barney', 'fred']
// The `_.matchesProperty` iteratee shorthand.
_.dropRightWhile(['active', false], users);
// => objects for ['barney']
// The `_.property` iteratee shorthand.
_.dropRightWhile('active', users);
// => objects for ['barney', 'fred', 'pebbles']
Creates a slice of array
excluding elements dropped from the beginning.
Elements are dropped until predicate
returns falsey. The predicate is
invoked with three arguments: (value, index, array).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.array
(Array): The array to query.
(Array): Returns the slice of array
.
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': true }
];
_.dropWhile(function(o) { return !o.active; }, users);
// => objects for ['pebbles']
// The `_.matches` iteratee shorthand.
_.dropWhile({ 'user': 'barney', 'active': false }, users);
// => objects for ['fred', 'pebbles']
// The `_.matchesProperty` iteratee shorthand.
_.dropWhile(['active', false], users);
// => objects for ['pebbles']
// The `_.property` iteratee shorthand.
_.dropWhile('active', users);
// => objects for ['barney', 'fred', 'pebbles']
Fills elements of array
with value
from start
up to, but not
including, end
.
Note: This method mutates array
.
[start=0]
(number): The start position.[end=array.length]
(number): The end position.value
(*): The value to fillarray
with.array
(Array): The array to fill.
(Array): Returns array
.
var array = [1, 2, 3];
_.fill('a', array);
console.log(array);
// => ['a', 'a', 'a']
_.fill(2, Array(3));
// => [2, 2, 2]
_.fill(1, 3, '*', [4, 6, 8, 10]);
// => [4, '*', '*', 10]
This method is like _.find
except that it returns the index of the first
element predicate
returns truthy for instead of the element itself.
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.array
(Array): The array to search.
(number): Returns the index of the found element, else -1
.
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': true }
];
_.findIndex(function(o) { return o.user == 'barney'; }, users);
// => 0
// The `_.matches` iteratee shorthand.
_.findIndex({ 'user': 'fred', 'active': false }, users);
// => 1
// The `_.matchesProperty` iteratee shorthand.
_.findIndex(['active', false], users);
// => 0
// The `_.property` iteratee shorthand.
_.findIndex('active', users);
// => 2
This method is like _.findIndex
except that it iterates over elements
of collection
from right to left.
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.array
(Array): The array to search.
(number): Returns the index of the found element, else -1
.
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.findLastIndex(function(o) { return o.user == 'pebbles'; }, users);
// => 2
// The `_.matches` iteratee shorthand.
_.findLastIndex({ 'user': 'barney', 'active': true }, users);
// => 0
// The `_.matchesProperty` iteratee shorthand.
_.findLastIndex(['active', false], users);
// => 2
// The `_.property` iteratee shorthand.
_.findLastIndex('active', users);
// => 0
Flattens array
a single level.
array
(Array): The array to flatten.
(Array): Returns the new flattened array.
_.flatten([1, [2, 3, [4]]]);
// => [1, 2, 3, [4]]
This method is like _.flatten
except that it recursively flattens array
.
array
(Array): The array to recursively flatten.
(Array): Returns the new flattened array.
_.flattenDeep([1, [2, 3, [4]]]);
// => [1, 2, 3, 4]
The inverse of _.toPairs
; this method returns an object composed
from key-value pairs
.
pairs
(Array): The key-value pairs.
(Object): Returns the new object.
_.fromPairs([['fred', 30], ['barney', 40]]);
// => { 'fred': 30, 'barney': 40 }
Gets the first element of array
.
_.first
array
(Array): The array to query.
(*): Returns the first element of array
.
_.head([1, 2, 3]);
// => 1
_.head([]);
// => undefined
Gets the index at which the first occurrence of value
is found in array
using SameValueZero
for equality comparisons. If fromIndex
is negative, it's used as the offset
from the end of array
.
[fromIndex=0]
(number): The index to search from.value
(*): The value to search for.array
(Array): The array to search.
(number): Returns the index of the matched value, else -1
.
_.indexOf(2, [1, 2, 1, 2]);
// => 1
// Search from the `fromIndex`.
_.indexOf(2, 2, [1, 2, 1, 2]);
// => 3
Gets all but the last element of array
.
array
(Array): The array to query.
(Array): Returns the slice of array
.
_.initial([1, 2, 3]);
// => [1, 2]
Creates an array of unique values that are included in all of the provided
arrays using SameValueZero
for equality comparisons.
[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of shared values.
_.intersection([1, 2], [4, 2], [2, 1]);
// => [2]
This method is like _.intersection
except that it accepts iteratee
which is invoked for each element of each arrays
to generate the criterion
by which uniqueness is computed. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of shared values.
_.intersectionBy(Math.floor, [4.3, 2.4], [2.1, 1.2]);
// => [2.1]
// The `_.property` iteratee shorthand.
_.intersectionBy('x', [{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }]);
// => [{ 'x': 1 }]
This method is like _.intersection
except that it accepts comparator
which is invoked to compare elements of arrays
. The comparator is invoked
with two arguments: (arrVal, othVal).
[comparator]
(Function): The comparator invoked per element.[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of shared values.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.intersectionWith(_.isEqual, others, objects);
// => [{ 'x': 1, 'y': 2 }]
Converts all elements in array
into a string separated by separator
.
[separator=',']
(string): The element separator.array
(Array): The array to convert.
(string): Returns the joined string.
_.join('~', ['a', 'b', 'c']);
// => 'a~b~c'
Gets the last element of array
.
array
(Array): The array to query.
(*): Returns the last element of array
.
_.last([1, 2, 3]);
// => 3
This method is like _.indexOf
except that it iterates over elements of
array
from right to left.
[fromIndex=array.length-1]
(number): The index to search from.value
(*): The value to search for.array
(Array): The array to search.
(number): Returns the index of the matched value, else -1
.
_.lastIndexOf(2, [1, 2, 1, 2]);
// => 3
// Search from the `fromIndex`.
_.lastIndexOf(2, 2, [1, 2, 1, 2]);
// => 1
Removes all provided values from array
using
SameValueZero
for equality comparisons.
Note: Unlike _.without
, this method mutates array
.
[values]
(...*): The values to remove.array
(Array): The array to modify.
(Array): Returns array
.
var array = [1, 2, 3, 1, 2, 3];
_.pull(3, 2, array);
console.log(array);
// => [1, 1]
This method is like _.pull
except that it accepts an array of values to remove.
Note: Unlike _.difference
, this method mutates array
.
values
(Array): The values to remove.array
(Array): The array to modify.
(Array): Returns array
.
var array = [1, 2, 3, 1, 2, 3];
_.pullAll([2, 3], array);
console.log(array);
// => [1, 1]
This method is like _.pullAll
except that it accepts iteratee
which is
invoked for each element of array
and values
to generate the criterion
by which uniqueness is computed. The iteratee is invoked with one argument: (value).
Note: Unlike _.differenceBy
, this method mutates array
.
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.values
(Array): The values to remove.array
(Array): The array to modify.
(Array): Returns array
.
var array = [{ 'x': 1 }, { 'x': 2 }, { 'x': 3 }, { 'x': 1 }];
_.pullAllBy('x', [{ 'x': 1 }, { 'x': 3 }], array);
console.log(array);
// => [{ 'x': 2 }]
Removes elements from array
corresponding to indexes
and returns an
array of removed elements.
Note: Unlike _.at
, this method mutates array
.
[indexes]
(...(number|number[]): The indexes of elements to remove, specified individually or in arrays.array
(Array): The array to modify.
(Array): Returns the new array of removed elements.
var array = [5, 10, 15, 20];
var evens = _.pullAt(3, 1, array);
console.log(array);
// => [5, 15]
console.log(evens);
// => [10, 20]
Removes all elements from array
that predicate
returns truthy for
and returns an array of the removed elements. The predicate is invoked with
three arguments: (value, index, array).
Note: Unlike _.filter
, this method mutates array
.
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.array
(Array): The array to modify.
(Array): Returns the new array of removed elements.
var array = [1, 2, 3, 4];
var evens = _.remove(function(n) {
return n % 2 == 0;
}, array);
console.log(array);
// => [1, 3]
console.log(evens);
// => [2, 4]
Reverses array
so that the first element becomes the last, the second
element becomes the second to last, and so on.
Note: This method mutates array
and is based on
Array#reverse
.
(Array): Returns array
.
var array = [1, 2, 3];
_.reverse(array);
// => [3, 2, 1]
console.log(array);
// => [3, 2, 1]
Creates a slice of array
from start
up to, but not including, end
.
Note: This method is used instead of Array#slice
to ensure dense arrays are returned.
[start=0]
(number): The start position.[end=array.length]
(number): The end position.array
(Array): The array to slice.
(Array): Returns the slice of array
.
Uses a binary search to determine the lowest index at which value
should
be inserted into array
in order to maintain its sort order.
value
(*): The value to evaluate.array
(Array): The sorted array to inspect.
(number): Returns the index at which value
should be inserted into array
.
_.sortedIndex(40, [30, 50]);
// => 1
_.sortedIndex(4, [4, 5]);
// => 0
This method is like _.sortedIndex
except that it accepts iteratee
which is invoked for value
and each element of array
to compute their
sort ranking. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.value
(*): The value to evaluate.array
(Array): The sorted array to inspect.
(number): Returns the index at which value
should be inserted into array
.
var dict = { 'thirty': 30, 'forty': 40, 'fifty': 50 };
_.sortedIndexBy(_.propertyOf(dict), 'forty', ['thirty', 'fifty']);
// => 1
// The `_.property` iteratee shorthand.
_.sortedIndexBy('x', { 'x': 4 }, [{ 'x': 4 }, { 'x': 5 }]);
// => 0
This method is like _.indexOf
except that it performs a binary
search on a sorted array
.
value
(*): The value to search for.array
(Array): The array to search.
(number): Returns the index of the matched value, else -1
.
_.sortedIndexOf(2, [1, 1, 2, 2]);
// => 2
This method is like _.sortedIndex
except that it returns the highest
index at which value
should be inserted into array
in order to
maintain its sort order.
value
(*): The value to evaluate.array
(Array): The sorted array to inspect.
(number): Returns the index at which value
should be inserted into array
.
_.sortedLastIndex(4, [4, 5]);
// => 1
This method is like _.sortedLastIndex
except that it accepts iteratee
which is invoked for value
and each element of array
to compute their
sort ranking. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.value
(*): The value to evaluate.array
(Array): The sorted array to inspect.
(number): Returns the index at which value
should be inserted into array
.
// The `_.property` iteratee shorthand.
_.sortedLastIndexBy('x', { 'x': 4 }, [{ 'x': 4 }, { 'x': 5 }]);
// => 1
This method is like _.lastIndexOf
except that it performs a binary
search on a sorted array
.
value
(*): The value to search for.array
(Array): The array to search.
(number): Returns the index of the matched value, else -1
.
_.sortedLastIndexOf(2, [1, 1, 2, 2]);
// => 3
This method is like _.uniq
except that it's designed and optimized
for sorted arrays.
array
(Array): The array to inspect.
(Array): Returns the new duplicate free array.
_.sortedUniq([1, 1, 2]);
// => [1, 2]
This method is like _.uniqBy
except that it's designed and optimized
for sorted arrays.
[iteratee]
(Function): The iteratee invoked per element.array
(Array): The array to inspect.
(Array): Returns the new duplicate free array.
_.sortedUniqBy(Math.floor, [1.1, 1.2, 2.3, 2.4]);
// => [1.1, 2.3]
Gets all but the first element of array
.
array
(Array): The array to query.
(Array): Returns the slice of array
.
_.tail([1, 2, 3]);
// => [2, 3]
Creates a slice of array
with n
elements taken from the beginning.
[n=1]
(number): The number of elements to take.array
(Array): The array to query.
(Array): Returns the slice of array
.
_.take([1, 2, 3]);
// => [1]
_.take(2, [1, 2, 3]);
// => [1, 2]
_.take(5, [1, 2, 3]);
// => [1, 2, 3]
_.take(0, [1, 2, 3]);
// => []
Creates a slice of array
with n
elements taken from the end.
[n=1]
(number): The number of elements to take.array
(Array): The array to query.
(Array): Returns the slice of array
.
_.takeRight([1, 2, 3]);
// => [3]
_.takeRight(2, [1, 2, 3]);
// => [2, 3]
_.takeRight(5, [1, 2, 3]);
// => [1, 2, 3]
_.takeRight(0, [1, 2, 3]);
// => []
Creates a slice of array
with elements taken from the end. Elements are
taken until predicate
returns falsey. The predicate is invoked with three
arguments: (value, index, array).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.array
(Array): The array to query.
(Array): Returns the slice of array
.
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false },
{ 'user': 'pebbles', 'active': false }
];
_.takeRightWhile(function(o) { return !o.active; }, users);
// => objects for ['fred', 'pebbles']
// The `_.matches` iteratee shorthand.
_.takeRightWhile({ 'user': 'pebbles', 'active': false }, users);
// => objects for ['pebbles']
// The `_.matchesProperty` iteratee shorthand.
_.takeRightWhile(['active', false], users);
// => objects for ['fred', 'pebbles']
// The `_.property` iteratee shorthand.
_.takeRightWhile('active', users);
// => []
Creates a slice of array
with elements taken from the beginning. Elements
are taken until predicate
returns falsey. The predicate is invoked with
three arguments: (value, index, array).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.array
(Array): The array to query.
(Array): Returns the slice of array
.
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false},
{ 'user': 'pebbles', 'active': true }
];
_.takeWhile(function(o) { return !o.active; }, users);
// => objects for ['barney', 'fred']
// The `_.matches` iteratee shorthand.
_.takeWhile({ 'user': 'barney', 'active': false }, users);
// => objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.takeWhile(['active', false], users);
// => objects for ['barney', 'fred']
// The `_.property` iteratee shorthand.
_.takeWhile('active', users);
// => []
Creates an array of unique values, in order, from all of the provided arrays
using SameValueZero
for equality comparisons.
[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of combined values.
_.union([1, 2], [4, 2], [2, 1]);
// => [2, 1, 4]
This method is like _.union
except that it accepts iteratee
which is
invoked for each element of each arrays
to generate the criterion by which
uniqueness is computed. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of combined values.
_.unionBy(Math.floor, [4.3, 2.4], [2.1, 1.2]);
// => [2.1, 1.2, 4.3]
// The `_.property` iteratee shorthand.
_.unionBy('x', [{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }]);
// => [{ 'x': 1 }, { 'x': 2 }]
This method is like _.union
except that it accepts comparator
which
is invoked to compare elements of arrays
. The comparator is invoked
with two arguments: (arrVal, othVal).
[comparator]
(Function): The comparator invoked per element.[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of combined values.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.unionWith(_.isEqual, others, objects);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
Creates a duplicate-free version of an array, using
SameValueZero
for equality comparisons, in which only the first occurrence of each element
is kept.
array
(Array): The array to inspect.
(Array): Returns the new duplicate free array.
_.uniq([2, 1, 2]);
// => [2, 1]
This method is like _.uniq
except that it accepts iteratee
which is
invoked for each element in array
to generate the criterion by which
uniqueness is computed. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.array
(Array): The array to inspect.
(Array): Returns the new duplicate free array.
_.uniqBy(Math.floor, [2.1, 1.2, 2.3]);
// => [2.1, 1.2]
// The `_.property` iteratee shorthand.
_.uniqBy('x', [{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }]);
// => [{ 'x': 1 }, { 'x': 2 }]
This method is like _.uniq
except that it accepts comparator
which
is invoked to compare elements of array
. The comparator is invoked with
two arguments: (arrVal, othVal).
[comparator]
(Function): The comparator invoked per element.array
(Array): The array to inspect.
(Array): Returns the new duplicate free array.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.uniqWith(_.isEqual, objects);
// => [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }]
This method is like _.zip
except that it accepts an array of grouped
elements and creates an array regrouping the elements to their pre-zip
configuration.
array
(Array): The array of grouped elements to process.
(Array): Returns the new array of regrouped elements.
var zipped = _.zip(['fred', 'barney'], [30, 40], [true, false]);
// => [['fred', 30, true], ['barney', 40, false]]
_.unzip(zipped);
// => [['fred', 'barney'], [30, 40], [true, false]]
This method is like _.unzip
except that it accepts iteratee
to specify
how regrouped values should be combined. The iteratee is invoked with the
elements of each group: (...group).
[iteratee=_.identity]
(Function): The function to combine regrouped values.array
(Array): The array of grouped elements to process.
(Array): Returns the new array of regrouped elements.
var zipped = _.zip([1, 2], [10, 20], [100, 200]);
// => [[1, 10, 100], [2, 20, 200]]
_.unzipWith(_.add, zipped);
// => [3, 30, 300]
Creates an array excluding all provided values using
SameValueZero
for equality comparisons.
[values]
(...*): The values to exclude.array
(Array): The array to filter.
(Array): Returns the new array of filtered values.
_.without(2, 1, [1, 2, 1, 3]);
// => [3]
Creates an array of unique values that is the symmetric difference of the provided arrays.
[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of values.
_.xor([4, 2], [2, 1]);
// => [1, 4]
This method is like _.xor
except that it accepts iteratee
which is
invoked for each element of each arrays
to generate the criterion by which
uniqueness is computed. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of values.
_.xorBy(Math.floor, [4.3, 2.4], [2.1, 1.2]);
// => [1.2, 4.3]
// The `_.property` iteratee shorthand.
_.xorBy('x', [{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }]);
// => [{ 'x': 2 }]
This method is like _.xor
except that it accepts comparator
which is
invoked to compare elements of arrays
. The comparator is invoked with
two arguments: (arrVal, othVal).
[comparator]
(Function): The comparator invoked per element.[arrays]
(...Array): The arrays to inspect.
(Array): Returns the new array of values.
var objects = [{ 'x': 1, 'y': 2 }, { 'x': 2, 'y': 1 }];
var others = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
_.xorWith(_.isEqual, others, objects);
// => [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 1 }]
Creates an array of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on.
[arrays]
(...Array): The arrays to process.
(Array): Returns the new array of grouped elements.
_.zip(['fred', 'barney'], [30, 40], [true, false]);
// => [['fred', 30, true], ['barney', 40, false]]
This method is like _.fromPairs
except that it accepts two arrays,
one of property names and one of corresponding values.
[props=[]]
(Array): The property names.[values=[]]
(Array): The property values.
(Object): Returns the new object.
_.zipObject(['a', 'b'], [1, 2]);
// => { 'a': 1, 'b': 2 }
This method is like _.zipObject
except that it supports property paths.
[values=[]]
(Array): The property values.[props=[]]
(Array): The property names.
(Object): Returns the new object.
_.zipObjectDeep([1, 2], ['a.b[0].c', 'a.b[1].d']);
// => { 'a': { 'b': [{ 'c': 1 }, { 'd': 2 }] } }
This method is like _.zip
except that it accepts iteratee
to specify
how grouped values should be combined. The iteratee is invoked with the
elements of each group: (...group).
[iteratee=_.identity]
(Function): The function to combine grouped values.[arrays]
(...Array): The arrays to process.
(Array): Returns the new array of grouped elements.
_.zipWith([100, 200], function(a, b, c) {
return a + b + c;
}, [10, 20], [1, 2]);
// => [111, 222]
Creates an object composed of keys generated from the results of running
each element of collection
through iteratee
. The corresponding value
of each key is the number of times the key was returned by iteratee
.
The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee to transform keys.collection
(Array|Object): The collection to iterate over.
(Object): Returns the composed aggregate object.
_.countBy(Math.floor, [6.1, 4.2, 6.3]);
// => { '4': 1, '6': 2 }
_.countBy('length', ['one', 'two', 'three']);
// => { '3': 2, '5': 1 }
Checks if predicate
returns truthy for all elements of collection
.
Iteration is stopped once predicate
returns falsey. The predicate is
invoked with three arguments: (value, index|key, collection).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(boolean): Returns true
if all elements pass the predicate check, else false
.
_.every(Boolean, [true, 1, null, 'yes']);
// => false
var users = [
{ 'user': 'barney', 'active': false },
{ 'user': 'fred', 'active': false }
];
// The `_.matches` iteratee shorthand.
_.every({ 'user': 'barney', 'active': false }, users);
// => false
// The `_.matchesProperty` iteratee shorthand.
_.every(['active', false], users);
// => true
// The `_.property` iteratee shorthand.
_.every('active', users);
// => false
Iterates over elements of collection
, returning an array of all elements
predicate
returns truthy for. The predicate is invoked with three arguments:
(value, index|key, collection).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(Array): Returns the new filtered array.
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false }
];
_.filter(function(o) { return !o.active; }, users);
// => objects for ['fred']
// The `_.matches` iteratee shorthand.
_.filter({ 'age': 36, 'active': true }, users);
// => objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.filter(['active', false], users);
// => objects for ['fred']
// The `_.property` iteratee shorthand.
_.filter('active', users);
// => objects for ['barney']
Iterates over elements of collection
, returning the first element
predicate
returns truthy for. The predicate is invoked with three arguments:
(value, index|key, collection).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to search.
(*): Returns the matched element, else undefined
.
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false },
{ 'user': 'pebbles', 'age': 1, 'active': true }
];
_.find(function(o) { return o.age < 40; }, users);
// => object for 'barney'
// The `_.matches` iteratee shorthand.
_.find({ 'age': 1, 'active': true }, users);
// => object for 'pebbles'
// The `_.matchesProperty` iteratee shorthand.
_.find(['active', false], users);
// => object for 'fred'
// The `_.property` iteratee shorthand.
_.find('active', users);
// => object for 'barney'
This method is like _.find
except that it iterates over elements of
collection
from right to left.
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to search.
(*): Returns the matched element, else undefined
.
_.findLast(function(n) {
return n % 2 == 1;
}, [1, 2, 3, 4]);
// => 3
Creates an array of flattened values by running each element in collection
through iteratee
and concating its result to the other mapped values.
The iteratee is invoked with three arguments: (value, index|key, collection).
[iteratee=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(Array): Returns the new flattened array.
function duplicate(n) {
return [n, n];
}
_.flatMap(duplicate, [1, 2]);
// => [1, 1, 2, 2]
Iterates over elements of collection
invoking iteratee
for each element.
The iteratee is invoked with three arguments: (value, index|key, collection).
Iteratee functions may exit iteration early by explicitly returning false
.
Note: As with other "Collections" methods, objects with a "length" property
are iterated like arrays. To avoid this behavior use _.forIn
or _.forOwn
for object iteration.
_.each
[iteratee=_.identity]
(Function): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(Array|Object): Returns collection
.
_([1, 2]).forEach(function(value) {
console.log(value);
});
// => logs `1` then `2`
_.forEach(function(value, key) {
console.log(key);
}, { 'a': 1, 'b': 2 });
// => logs 'a' then 'b' (iteration order is not guaranteed)
This method is like _.forEach
except that it iterates over elements of
collection
from right to left.
_.eachRight
[iteratee=_.identity]
(Function): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(Array|Object): Returns collection
.
_.forEachRight(function(value) {
console.log(value);
}, [1, 2]);
// => logs `2` then `1`
Creates an object composed of keys generated from the results of running
each element of collection
through iteratee
. The corresponding value
of each key is an array of elements responsible for generating the key.
The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee to transform keys.collection
(Array|Object): The collection to iterate over.
(Object): Returns the composed aggregate object.
_.groupBy(Math.floor, [6.1, 4.2, 6.3]);
// => { '4': [4.2], '6': [6.1, 6.3] }
// The `_.property` iteratee shorthand.
_.groupBy('length', ['one', 'two', 'three']);
// => { '3': ['one', 'two'], '5': ['three'] }
Checks if value
is in collection
. If collection
is a string it's checked
for a substring of value
, otherwise SameValueZero
is used for equality comparisons. If fromIndex
is negative, it's used as
the offset from the end of collection
.
[fromIndex=0]
(number): The index to search from.value
(*): The value to search for.collection
(Array|Object|string): The collection to search.
(boolean): Returns true
if value
is found, else false
.
_.includes(1, [1, 2, 3]);
// => true
_.includes(2, 1, [1, 2, 3]);
// => false
_.includes('fred', { 'user': 'fred', 'age': 40 });
// => true
_.includes('eb', 'pebbles');
// => true
Invokes the method at path
of each element in collection
, returning
an array of the results of each invoked method. Any additional arguments
are provided to each invoked method. If methodName
is a function it's
invoked for, and this
bound to, each element in collection
.
[args]
(...*): The arguments to invoke each method with.path
(Array|Function|string): The path of the method to invoke or the function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(Array): Returns the array of results.
_.invokeMap('sort', [[5, 1, 7], [3, 2, 1]]);
// => [[1, 5, 7], [1, 2, 3]]
_.invokeMap('', String.prototype.split, [123, 456]);
// => [['1', '2', '3'], ['4', '5', '6']]
Creates an object composed of keys generated from the results of running
each element of collection
through iteratee
. The corresponding value
of each key is the last element responsible for generating the key. The
iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee to transform keys.collection
(Array|Object): The collection to iterate over.
(Object): Returns the composed aggregate object.
var array = [
{ 'dir': 'left', 'code': 97 },
{ 'dir': 'right', 'code': 100 }
];
_.keyBy(function(o) {
return String.fromCharCode(o.code);
}, array);
// => { 'a': { 'dir': 'left', 'code': 97 }, 'd': { 'dir': 'right', 'code': 100 } }
_.keyBy('dir', array);
// => { 'left': { 'dir': 'left', 'code': 97 }, 'right': { 'dir': 'right', 'code': 100 } }
Creates an array of values by running each element in collection
through
iteratee
. The iteratee is invoked with three arguments:
(value, index|key, collection).
Many lodash methods are guarded to work as iteratees for methods like
_.every
, _.filter
, _.map
, _.mapValues
, _.reject
, and _.some
.
The guarded methods are:
ary
, curry
, curryRight
, drop
, dropRight
, every
, fill
,
invert
, parseInt
, random
, range
, rangeRight
, slice
, some
,
sortBy
, take
, takeRight
, template
, trim
, trimEnd
, trimStart
,
and words
[iteratee=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(Array): Returns the new mapped array.
function square(n) {
return n * n;
}
_.map(square, [4, 8]);
// => [16, 64]
_.map(square, { 'a': 4, 'b': 8 });
// => [16, 64] (iteration order is not guaranteed)
var users = [
{ 'user': 'barney' },
{ 'user': 'fred' }
];
// The `_.property` iteratee shorthand.
_.map('user', users);
// => ['barney', 'fred']
This method is like _.sortBy
except that it allows specifying the sort
orders of the iteratees to sort by. If orders
is unspecified, all values
are sorted in ascending order. Otherwise, specify an order of "desc" for
descending or "asc" for ascending sort order of corresponding values.
[orders]
(string[]): The sort orders ofiteratees
.[iteratees=[_.identity]]
(Function[]|Object[]|string[]): The iteratees to sort by.collection
(Array|Object): The collection to iterate over.
(Array): Returns the new sorted array.
var users = [
{ 'user': 'fred', 'age': 48 },
{ 'user': 'barney', 'age': 34 },
{ 'user': 'fred', 'age': 42 },
{ 'user': 'barney', 'age': 36 }
];
// Sort by `user` in ascending order and by `age` in descending order.
_.orderBy(['asc', 'desc'], ['user', 'age'], users);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
Creates an array of elements split into two groups, the first of which
contains elements predicate
returns truthy for, the second of which
contains elements predicate
returns falsey for. The predicate is
invoked with one argument: (value).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(Array): Returns the array of grouped elements.
var users = [
{ 'user': 'barney', 'age': 36, 'active': false },
{ 'user': 'fred', 'age': 40, 'active': true },
{ 'user': 'pebbles', 'age': 1, 'active': false }
];
_.partition(function(o) { return o.active; }, users);
// => objects for [['fred'], ['barney', 'pebbles']]
// The `_.matches` iteratee shorthand.
_.partition({ 'age': 1, 'active': false }, users);
// => objects for [['pebbles'], ['barney', 'fred']]
// The `_.matchesProperty` iteratee shorthand.
_.partition(['active', false], users);
// => objects for [['barney', 'pebbles'], ['fred']]
// The `_.property` iteratee shorthand.
_.partition('active', users);
// => objects for [['fred'], ['barney', 'pebbles']]
Reduces collection
to a value which is the accumulated result of running
each element in collection
through iteratee
, where each successive
invocation is supplied the return value of the previous. If accumulator
is not provided the first element of collection
is used as the initial
value. The iteratee is invoked with four arguments:
(accumulator, value, index|key, collection).
Many lodash methods are guarded to work as iteratees for methods like
_.reduce
, _.reduceRight
, and _.transform
.
The guarded methods are:
assign
, defaults
, defaultsDeep
, includes
, merge
, orderBy
,
and sortBy
[iteratee=_.identity]
(Function): The function invoked per iteration.[accumulator]
(*): The initial value.collection
(Array|Object): The collection to iterate over.
(*): Returns the accumulated value.
_.reduce(function(sum, n) {
return sum + n;
}, 0, [1, 2]);
// => 3
_.reduce(function(result, value, key) {
(result[value] || (result[value] = [])).push(key);
return result;
}, {}, { 'a': 1, 'b': 2, 'c': 1 });
// => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)
This method is like _.reduce
except that it iterates over elements of
collection
from right to left.
[iteratee=_.identity]
(Function): The function invoked per iteration.[accumulator]
(*): The initial value.collection
(Array|Object): The collection to iterate over.
(*): Returns the accumulated value.
var array = [[0, 1], [2, 3], [4, 5]];
_.reduceRight(function(flattened, other) {
return flattened.concat(other);
}, [], array);
// => [4, 5, 2, 3, 0, 1]
The opposite of _.filter
; this method returns the elements of collection
that predicate
does not return truthy for.
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(Array): Returns the new filtered array.
var users = [
{ 'user': 'barney', 'age': 36, 'active': false },
{ 'user': 'fred', 'age': 40, 'active': true }
];
_.reject(function(o) { return !o.active; }, users);
// => objects for ['fred']
// The `_.matches` iteratee shorthand.
_.reject({ 'age': 40, 'active': true }, users);
// => objects for ['barney']
// The `_.matchesProperty` iteratee shorthand.
_.reject(['active', false], users);
// => objects for ['fred']
// The `_.property` iteratee shorthand.
_.reject('active', users);
// => objects for ['barney']
Gets a random element from collection
.
collection
(Array|Object): The collection to sample.
(*): Returns the random element.
_.sample([1, 2, 3, 4]);
// => 2
Gets n
random elements at unique keys from collection
up to the
size of collection
.
[n=0]
(number): The number of elements to sample.collection
(Array|Object): The collection to sample.
(Array): Returns the random elements.
_.sampleSize(2, [1, 2, 3]);
// => [3, 1]
_.sampleSize(4, [1, 2, 3]);
// => [2, 3, 1]
Creates an array of shuffled values, using a version of the Fisher-Yates shuffle.
collection
(Array|Object): The collection to shuffle.
(Array): Returns the new shuffled array.
_.shuffle([1, 2, 3, 4]);
// => [4, 1, 3, 2]
Gets the size of collection
by returning its length for array-like
values or the number of own enumerable properties for objects.
collection
(Array|Object): The collection to inspect.
(number): Returns the collection size.
_.size([1, 2, 3]);
// => 3
_.size({ 'a': 1, 'b': 2 });
// => 2
_.size('pebbles');
// => 7
Checks if predicate
returns truthy for any element of collection
.
Iteration is stopped once predicate
returns truthy. The predicate is
invoked with three arguments: (value, index|key, collection).
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.collection
(Array|Object): The collection to iterate over.
(boolean): Returns true
if any element passes the predicate check, else false
.
_.some(Boolean, [null, 0, 'yes', false]);
// => true
var users = [
{ 'user': 'barney', 'active': true },
{ 'user': 'fred', 'active': false }
];
// The `_.matches` iteratee shorthand.
_.some({ 'user': 'barney', 'active': false }, users);
// => false
// The `_.matchesProperty` iteratee shorthand.
_.some(['active', false], users);
// => true
// The `_.property` iteratee shorthand.
_.some('active', users);
// => true
Creates an array of elements, sorted in ascending order by the results of running each element in a collection through each iteratee. This method performs a stable sort, that is, it preserves the original sort order of equal elements. The iteratees are invoked with one argument: (value).
[iteratees=[_.identity]]
(...(Function|Function[]|Object|Object[]|string|string[]): The iteratees to sort by, specified individually or in arrays.collection
(Array|Object): The collection to iterate over.
(Array): Returns the new sorted array.
var users = [
{ 'user': 'fred', 'age': 48 },
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 42 },
{ 'user': 'barney', 'age': 34 }
];
_.sortBy(function(o) { return o.user; }, users);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
_.sortBy(['user', 'age'], users);
// => objects for [['barney', 34], ['barney', 36], ['fred', 42], ['fred', 48]]
_.sortBy(function(o) {
return Math.floor(o.age / 10);
}, 'user', users);
// => objects for [['barney', 36], ['barney', 34], ['fred', 48], ['fred', 42]]
Gets the timestamp of the number of milliseconds that have elapsed since the Unix epoch (1 January 1970 00:00:00 UTC).
(number): Returns the timestamp.
_.defer(_.now(), function(stamp) {
console.log(_.now() - stamp);
});
// => logs the number of milliseconds it took for the deferred function to be invoked
The opposite of _.before
; this method creates a function that invokes
func
once it's called n
or more times.
func
(Function): The function to restrict.n
(number): The number of calls beforefunc
is invoked.
(Function): Returns the new restricted function.
var saves = ['profile', 'settings'];
var done = _.after(function() {
console.log('done saving!');
}, saves.length);
_.forEach(function(type) {
asyncSave({ 'type': type, 'complete': done });
}, saves);
// => logs 'done saving!' after the two async saves have completed
Creates a function that accepts up to n
arguments, ignoring any
additional arguments.
[n=func.length]
(number): The arity cap.func
(Function): The function to cap arguments for.
(Function): Returns the new function.
_.map(_.ary(parseInt, 1), ['6', '8', '10']);
// => [6, 8, 10]
Creates a function that invokes func
, with the this
binding and arguments
of the created function, while it's called less than n
times. Subsequent
calls to the created function return the result of the last func
invocation.
func
(Function): The function to restrict.n
(number): The number of calls at whichfunc
is no longer invoked.
(Function): Returns the new restricted function.
jQuery(element).on('click', _.before(addContactToList, 5));
// => allows adding up to 4 contacts to the list
Creates a function that invokes func
with the this
binding of thisArg
and prepends any additional _.bind
arguments to those provided to the
bound function.
The _.bind.placeholder
value, which defaults to _
in monolithic builds,
may be used as a placeholder for partially applied arguments.
Note: Unlike native Function#bind
this method doesn't set the "length"
property of bound functions.
[partials]
(...*): The arguments to be partially applied.thisArg
(*): Thethis
binding offunc
.func
(Function): The function to bind.
(Function): Returns the new bound function.
var greet = function(greeting, punctuation) {
return greeting + ' ' + this.user + punctuation;
};
var object = { 'user': 'fred' };
var bound = _.bind('hi', object, greet);
bound('!');
// => 'hi fred!'
// Bound with placeholders.
var bound = _.bind(_, '!', object, greet);
bound('hi');
// => 'hi fred!'
Creates a function that invokes the method at object[key]
and prepends
any additional _.bindKey
arguments to those provided to the bound function.
This method differs from _.bind
by allowing bound functions to reference
methods that may be redefined or don't yet exist.
See Peter Michaux's article
for more details.
The _.bindKey.placeholder
value, which defaults to _
in monolithic
builds, may be used as a placeholder for partially applied arguments.
[partials]
(...*): The arguments to be partially applied.key
(string): The key of the method.object
(Object): The object to invoke the method on.
(Function): Returns the new bound function.
var object = {
'user': 'fred',
'greet': function(greeting, punctuation) {
return greeting + ' ' + this.user + punctuation;
}
};
var bound = _.bindKey('hi', 'greet', object);
bound('!');
// => 'hi fred!'
object.greet = function(greeting, punctuation) {
return greeting + 'ya ' + this.user + punctuation;
};
bound('!');
// => 'hiya fred!'
// Bound with placeholders.
var bound = _.bindKey(_, '!', 'greet', object);
bound('hi');
// => 'hiya fred!'
Creates a function that accepts arguments of func
and either invokes
func
returning its result, if at least arity
number of arguments have
been provided, or returns a function that accepts the remaining func
arguments, and so on. The arity of func
may be specified if func.length
is not sufficient.
The _.curry.placeholder
value, which defaults to _
in monolithic builds,
may be used as a placeholder for provided arguments.
Note: This method doesn't set the "length" property of curried functions.
[arity=func.length]
(number): The arity offunc
.func
(Function): The function to curry.
(Function): Returns the new curried function.
var abc = function(a, b, c) {
return [a, b, c];
};
var curried = _.curry(abc);
curried(1)(2)(3);
// => [1, 2, 3]
curried(1, 2)(3);
// => [1, 2, 3]
curried(1, 2, 3);
// => [1, 2, 3]
// Curried with placeholders.
curried(1)(_, 3)(2);
// => [1, 2, 3]
This method is like _.curry
except that arguments are applied to func
in the manner of _.partialRight
instead of _.partial
.
The _.curryRight.placeholder
value, which defaults to _
in monolithic
builds, may be used as a placeholder for provided arguments.
Note: This method doesn't set the "length" property of curried functions.
[arity=func.length]
(number): The arity offunc
.func
(Function): The function to curry.
(Function): Returns the new curried function.
var abc = function(a, b, c) {
return [a, b, c];
};
var curried = _.curryRight(abc);
curried(3)(2)(1);
// => [1, 2, 3]
curried(2, 3)(1);
// => [1, 2, 3]
curried(1, 2, 3);
// => [1, 2, 3]
// Curried with placeholders.
curried(3)(1, _)(2);
// => [1, 2, 3]
Creates a debounced function that delays invoking func
until after wait
milliseconds have elapsed since the last time the debounced function was
invoked. The debounced function comes with a cancel
method to cancel
delayed func
invocations and a flush
method to immediately invoke them.
Provide an options object to indicate whether func
should be invoked on
the leading and/or trailing edge of the wait
timeout. The func
is invoked
with the last arguments provided to the debounced function. Subsequent calls
to the debounced function return the result of the last func
invocation.
Note: If leading
and trailing
options are true
, func
is invoked
on the trailing edge of the timeout only if the debounced function is
invoked more than once during the wait
timeout.
See David Corbacho's article
for details over the differences between _.debounce
and _.throttle
.
func
(Function): The function to debounce.[wait=0]
(number): The number of milliseconds to delay.[options]
(Object): The options object.[options.leading=false]
(boolean): Specify invoking on the leading edge of the timeout.[options.maxWait]
(number): The maximum timefunc
is allowed to be delayed before it's invoked.[options.trailing=true]
(boolean): Specify invoking on the trailing edge of the timeout.
(Function): Returns the new debounced function.
// Avoid costly calculations while the window size is in flux.
jQuery(window).on('resize', _.debounce(150, calculateLayout));
// Invoke `sendMail` when clicked, debouncing subsequent calls.
jQuery(element).on('click', _.debounce({
'leading': true,
'trailing': false
}, 300, sendMail));
// Ensure `batchLog` is invoked once after 1 second of debounced calls.
var debounced = _.debounce({ 'maxWait': 1000 }, 250, batchLog);
var source = new EventSource('/stream');
jQuery(source).on('message', debounced);
// Cancel the trailing debounced invocation.
jQuery(window).on('popstate', debounced.cancel);
Defers invoking the func
until the current call stack has cleared. Any
additional arguments are provided to func
when it's invoked.
[args]
(...*): The arguments to invokefunc
with.func
(Function): The function to defer.
(number): Returns the timer id.
_.defer('deferred', function(text) {
console.log(text);
});
// => logs 'deferred' after one or more milliseconds
Invokes func
after wait
milliseconds. Any additional arguments are
provided to func
when it's invoked.
[args]
(...*): The arguments to invokefunc
with.wait
(number): The number of milliseconds to delay invocation.func
(Function): The function to delay.
(number): Returns the timer id.
_.delay('later', 1000, function(text) {
console.log(text);
});
// => logs 'later' after one second
Creates a function that invokes func
with arguments reversed.
func
(Function): The function to flip arguments for.
(Function): Returns the new function.
var flipped = _.flip(function() {
return _.toArray(arguments);
});
flipped('a', 'b', 'c', 'd');
// => ['d', 'c', 'b', 'a']
Creates a function that memoizes the result of func
. If resolver
is
provided it determines the cache key for storing the result based on the
arguments provided to the memoized function. By default, the first argument
provided to the memoized function is used as the map cache key. The func
is invoked with the this
binding of the memoized function.
Note: The cache is exposed as the cache
property on the memoized
function. Its creation may be customized by replacing the _.memoize.Cache
constructor with one whose instances implement the Map
method interface of delete
, get
, has
, and set
.
[resolver]
(Function): The function to resolve the cache key.func
(Function): The function to have its output memoized.
(Function): Returns the new memoizing function.
var object = { 'a': 1, 'b': 2 };
var other = { 'c': 3, 'd': 4 };
var values = _.memoize(_.values);
values(object);
// => [1, 2]
values(other);
// => [3, 4]
object.a = 2;
values(object);
// => [1, 2]
// Modify the result cache.
values.cache.set(object, ['a', 'b']);
values(object);
// => ['a', 'b']
// Replace `_.memoize.Cache`.
_.memoize.Cache = WeakMap;
Creates a function that negates the result of the predicate func
. The
func
predicate is invoked with the this
binding and arguments of the
created function.
predicate
(Function): The predicate to negate.
(Function): Returns the new function.
function isEven(n) {
return n % 2 == 0;
}
_.filter(_.negate(isEven), [1, 2, 3, 4, 5, 6]);
// => [1, 3, 5]
Creates a function that is restricted to invoking func
once. Repeat calls
to the function return the value of the first invocation. The func
is
invoked with the this
binding and arguments of the created function.
func
(Function): The function to restrict.
(Function): Returns the new restricted function.
var initialize = _.once(createApplication);
initialize();
initialize();
// `initialize` invokes `createApplication` once
Creates a function that invokes func
with arguments transformed by
corresponding transforms
.
[transforms]
(...(Function|Function[]): The functions to transform arguments, specified individually or in arrays.func
(Function): The function to wrap.
(Function): Returns the new function.
function doubled(n) {
return n * 2;
}
function square(n) {
return n * n;
}
var func = _.overArgs(doubled, square, function(x, y) {
return [x, y];
});
func(9, 3);
// => [81, 6]
func(10, 5);
// => [100, 10]
Creates a function that invokes func
with partial
arguments prepended
to those provided to the new function. This method is like _.bind
except
it does not alter the this
binding.
The _.partial.placeholder
value, which defaults to _
in monolithic
builds, may be used as a placeholder for partially applied arguments.
Note: This method doesn't set the "length" property of partially
applied functions.
func
(Function): The function to partially apply arguments to.[partials]
(...*): The arguments to be partially applied.
(Function): Returns the new partially applied function.
var greet = function(greeting, name) {
return greeting + ' ' + name;
};
var sayHelloTo = _.partial(greet, 'hello');
sayHelloTo('fred');
// => 'hello fred'
// Partially applied with placeholders.
var greetFred = _.partial(greet, _, 'fred');
greetFred('hi');
// => 'hi fred'
This method is like _.partial
except that partially applied arguments
are appended to those provided to the new function.
The _.partialRight.placeholder
value, which defaults to _
in monolithic
builds, may be used as a placeholder for partially applied arguments.
Note: This method doesn't set the "length" property of partially
applied functions.
func
(Function): The function to partially apply arguments to.[partials]
(...*): The arguments to be partially applied.
(Function): Returns the new partially applied function.
var greet = function(greeting, name) {
return greeting + ' ' + name;
};
var greetFred = _.partialRight(greet, 'fred');
greetFred('hi');
// => 'hi fred'
// Partially applied with placeholders.
var sayHelloTo = _.partialRight(greet, 'hello', _);
sayHelloTo('fred');
// => 'hello fred'
Creates a function that invokes func
with arguments arranged according
to the specified indexes where the argument value at the first index is
provided as the first argument, the argument value at the second index is
provided as the second argument, and so on.
indexes
(...(number|number[]): The arranged argument indexes, specified individually or in arrays.func
(Function): The function to rearrange arguments for.
(Function): Returns the new function.
var rearged = _.rearg(0, 1, 2, function(a, b, c) {
return [a, b, c];
});
rearged('b', 'c', 'a')
// => ['a', 'b', 'c']
Creates a function that invokes func
with the this
binding of the
created function and arguments from start
and beyond provided as an array.
Note: This method is based on the rest parameter.
[start=func.length-1]
(number): The start position of the rest parameter.func
(Function): The function to apply a rest parameter to.
(Function): Returns the new function.
var say = _.rest(function(what, names) {
return what + ' ' + _.initial(names).join(', ') +
(_.size(names) > 1 ? ', & ' : '') + _.last(names);
});
say('hello', 'fred', 'barney', 'pebbles');
// => 'hello fred, barney, & pebbles'
Creates a function that invokes func
with the this
binding of the created
function and an array of arguments much like Function#apply
.
Note: This method is based on the spread operator.
[start=0]
(number): The start position of the spread.func
(Function): The function to spread arguments over.
(Function): Returns the new function.
var say = _.spread(function(who, what) {
return who + ' says ' + what;
});
say(['fred', 'hello']);
// => 'fred says hello'
var numbers = Promise.all([
Promise.resolve(40),
Promise.resolve(36)
]);
numbers.then(_.spread(function(x, y) {
return x + y;
}));
// => a Promise of 76
Creates a throttled function that only invokes func
at most once per
every wait
milliseconds. The throttled function comes with a cancel
method to cancel delayed func
invocations and a flush
method to
immediately invoke them. Provide an options object to indicate whether
func
should be invoked on the leading and/or trailing edge of the wait
timeout. The func
is invoked with the last arguments provided to the
throttled function. Subsequent calls to the throttled function return the
result of the last func
invocation.
Note: If leading
and trailing
options are true
, func
is invoked
on the trailing edge of the timeout only if the throttled function is
invoked more than once during the wait
timeout.
See David Corbacho's article
for details over the differences between _.throttle
and _.debounce
.
func
(Function): The function to throttle.[wait=0]
(number): The number of milliseconds to throttle invocations to.[options]
(Object): The options object.[options.leading=true]
(boolean): Specify invoking on the leading edge of the timeout.[options.trailing=true]
(boolean): Specify invoking on the trailing edge of the timeout.
(Function): Returns the new throttled function.
// Avoid excessively updating the position while scrolling.
jQuery(window).on('scroll', _.throttle(100, updatePosition));
// Invoke `renewToken` when the click event is fired, but not more than once every 5 minutes.
var throttled = _.throttle({ 'trailing': false }, 300000, renewToken);
jQuery(element).on('click', throttled);
// Cancel the trailing throttled invocation.
jQuery(window).on('popstate', throttled.cancel);
Creates a function that accepts up to one argument, ignoring any additional arguments.
func
(Function): The function to cap arguments for.
(Function): Returns the new function.
_.map(_.unary(parseInt), ['6', '8', '10']);
// => [6, 8, 10]
Creates a function that provides value
to the wrapper function as its
first argument. Any additional arguments provided to the function are
appended to those provided to the wrapper function. The wrapper is invoked
with the this
binding of the created function.
wrapper
(Function): The wrapper function.value
(*): The value to wrap.
(Function): Returns the new function.
var p = _.wrap(function(func, text) {
return '<p>' + func(text) + '</p>';
}, _.escape);
p('fred, barney, & pebbles');
// => '<p>fred, barney, & pebbles</p>'
Creates a shallow clone of value
.
Note: This method is loosely based on the
structured clone algorithm
and supports cloning arrays, array buffers, booleans, date objects, maps,
numbers, Object
objects, regexes, sets, strings, symbols, and typed
arrays. The own enumerable properties of arguments
objects are cloned
as plain objects. An empty object is returned for uncloneable values such
as error objects, functions, DOM nodes, and WeakMaps.
value
(*): The value to clone.
(*): Returns the cloned value.
var objects = [{ 'a': 1 }, { 'b': 2 }];
var shallow = _.clone(objects);
console.log(shallow[0] === objects[0]);
// => true
This method is like _.clone
except that it recursively clones value
.
value
(*): The value to recursively clone.
(*): Returns the deep cloned value.
var objects = [{ 'a': 1 }, { 'b': 2 }];
var deep = _.cloneDeep(objects);
console.log(deep[0] === objects[0]);
// => false
This method is like _.cloneWith
except that it recursively clones value
.
[customizer]
(Function): The function to customize cloning.value
(*): The value to recursively clone.
(*): Returns the deep cloned value.
function customizer(value) {
if (_.isElement(value)) {
return value.cloneNode(true);
}
}
var el = _.cloneDeepWith(customizer, document.body);
console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 20
This method is like _.clone
except that it accepts customizer
which
is invoked to produce the cloned value. If customizer
returns undefined
cloning is handled by the method instead. The customizer
is invoked with
up to four arguments; (value [, index|key, object, stack]).
[customizer]
(Function): The function to customize cloning.value
(*): The value to clone.
(*): Returns the cloned value.
function customizer(value) {
if (_.isElement(value)) {
return value.cloneNode(false);
}
}
var el = _.cloneWith(customizer, document.body);
console.log(el === document.body);
// => false
console.log(el.nodeName);
// => 'BODY'
console.log(el.childNodes.length);
// => 0
Performs a SameValueZero
comparison between two values to determine if they are equivalent.
other
(*): The other value to compare.value
(*): The value to compare.
(boolean): Returns true
if the values are equivalent, else false
.
var object = { 'user': 'fred' };
var other = { 'user': 'fred' };
_.eq(object, object);
// => true
_.eq(other, object);
// => false
_.eq('a', 'a');
// => true
_.eq(Object('a'), 'a');
// => false
_.eq(NaN, NaN);
// => true
Checks if value
is greater than other
.
other
(*): The other value to compare.value
(*): The value to compare.
(boolean): Returns true
if value
is greater than other
, else false
.
_.gt(1, 3);
// => true
_.gt(3, 3);
// => false
_.gt(3, 1);
// => false
Checks if value
is greater than or equal to other
.
other
(*): The other value to compare.value
(*): The value to compare.
(boolean): Returns true
if value
is greater than or equal to other
, else false
.
_.gte(1, 3);
// => true
_.gte(3, 3);
// => true
_.gte(3, 1);
// => false
Checks if value
is likely an arguments
object.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isArguments(function() { return arguments; }());
// => true
_.isArguments([1, 2, 3]);
// => false
Checks if value
is classified as an Array
object.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isArray([1, 2, 3]);
// => true
_.isArray(document.body.children);
// => false
_.isArray('abc');
// => false
_.isArray(_.noop);
// => false
Checks if value
is array-like. A value is considered array-like if it's
not a function and has a value.length
that's an integer greater than or
equal to 0
and less than or equal to Number.MAX_SAFE_INTEGER
.
value
(*): The value to check.
(boolean): Returns true
if value
is array-like, else false
.
_.isArrayLike([1, 2, 3]);
// => true
_.isArrayLike(document.body.children);
// => true
_.isArrayLike('abc');
// => true
_.isArrayLike(_.noop);
// => false
This method is like _.isArrayLike
except that it also checks if value
is an object.
value
(*): The value to check.
(boolean): Returns true
if value
is an array-like object, else false
.
_.isArrayLikeObject([1, 2, 3]);
// => true
_.isArrayLikeObject(document.body.children);
// => true
_.isArrayLikeObject('abc');
// => false
_.isArrayLikeObject(_.noop);
// => false
Checks if value
is classified as a boolean primitive or object.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isBoolean(false);
// => true
_.isBoolean(null);
// => false
Checks if value
is classified as a Date
object.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isDate(new Date);
// => true
_.isDate('Mon April 23 2012');
// => false
Checks if value
is likely a DOM element.
value
(*): The value to check.
(boolean): Returns true
if value
is a DOM element, else false
.
_.isElement(document.body);
// => true
_.isElement('<body>');
// => false
Checks if value
is empty. A value is considered empty unless it's an
arguments
object, array, string, or jQuery-like collection with a length
greater than 0
or an object with own enumerable properties.
value
(Array|Object|string): The value to inspect.
(boolean): Returns true
if value
is empty, else false
.
_.isEmpty(null);
// => true
_.isEmpty(true);
// => true
_.isEmpty(1);
// => true
_.isEmpty([1, 2, 3]);
// => false
_.isEmpty({ 'a': 1 });
// => false
Performs a deep comparison between two values to determine if they are
equivalent.
Note: This method supports comparing arrays, array buffers, booleans,
date objects, error objects, maps, numbers, Object
objects, regexes,
sets, strings, symbols, and typed arrays. Object
objects are compared
by their own, not inherited, enumerable properties. Functions and DOM
nodes are not supported.
other
(*): The other value to compare.value
(*): The value to compare.
(boolean): Returns true
if the values are equivalent, else false
.
var object = { 'user': 'fred' };
var other = { 'user': 'fred' };
_.isEqual(other, object);
// => true
object === other;
// => false
This method is like _.isEqual
except that it accepts customizer
which is
invoked to compare values. If customizer
returns undefined
comparisons are
handled by the method instead. The customizer
is invoked with up to six arguments:
(objValue, othValue [, index|key, object, other, stack]).
[customizer]
(Function): The function to customize comparisons.other
(*): The other value to compare.value
(*): The value to compare.
(boolean): Returns true
if the values are equivalent, else false
.
function isGreeting(value) {
return /^h(?:i|ello)$/.test(value);
}
function customizer(objValue, othValue) {
if (isGreeting(objValue) && isGreeting(othValue)) {
return true;
}
}
var array = ['hello', 'goodbye'];
var other = ['hi', 'goodbye'];
_.isEqualWith(customizer, other, array);
// => true
Checks if value
is an Error
, EvalError
, RangeError
, ReferenceError
,
SyntaxError
, TypeError
, or URIError
object.
value
(*): The value to check.
(boolean): Returns true
if value
is an error object, else false
.
_.isError(new Error);
// => true
_.isError(Error);
// => false
Checks if value
is a finite primitive number.
Note: This method is based on Number.isFinite
.
value
(*): The value to check.
(boolean): Returns true
if value
is a finite number, else false
.
_.isFinite(3);
// => true
_.isFinite(Number.MAX_VALUE);
// => true
_.isFinite(3.14);
// => true
_.isFinite(Infinity);
// => false
Checks if value
is classified as a Function
object.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isFunction(_);
// => true
_.isFunction(/abc/);
// => false
Checks if value
is an integer.
Note: This method is based on Number.isInteger
.
value
(*): The value to check.
(boolean): Returns true
if value
is an integer, else false
.
_.isInteger(3);
// => true
_.isInteger(Number.MIN_VALUE);
// => false
_.isInteger(Infinity);
// => false
_.isInteger('3');
// => false
Checks if value
is a valid array-like length.
Note: This function is loosely based on ToLength
.
value
(*): The value to check.
(boolean): Returns true
if value
is a valid length, else false
.
_.isLength(3);
// => true
_.isLength(Number.MIN_VALUE);
// => false
_.isLength(Infinity);
// => false
_.isLength('3');
// => false
Performs a deep comparison between object
and source
to determine if
object
contains equivalent property values.
Note: This method supports comparing the same values as _.isEqual
.
source
(Object): The object of property values to match.object
(Object): The object to inspect.
(boolean): Returns true
if object
is a match, else false
.
var object = { 'user': 'fred', 'age': 40 };
_.isMatch({ 'age': 40 }, object);
// => true
_.isMatch({ 'age': 36 }, object);
// => false
This method is like _.isMatch
except that it accepts customizer
which
is invoked to compare values. If customizer
returns undefined
comparisons
are handled by the method instead. The customizer
is invoked with five
arguments: (objValue, srcValue, index|key, object, source).
[customizer]
(Function): The function to customize comparisons.source
(Object): The object of property values to match.object
(Object): The object to inspect.
(boolean): Returns true
if object
is a match, else false
.
function isGreeting(value) {
return /^h(?:i|ello)$/.test(value);
}
function customizer(objValue, srcValue) {
if (isGreeting(objValue) && isGreeting(srcValue)) {
return true;
}
}
var object = { 'greeting': 'hello' };
var source = { 'greeting': 'hi' };
_.isMatchWith(customizer, source, object);
// => true
Checks if value
is NaN
.
Note: This method is not the same as isNaN
which returns true
for undefined
and other non-numeric values.
value
(*): The value to check.
(boolean): Returns true
if value
is NaN
, else false
.
_.isNaN(NaN);
// => true
_.isNaN(new Number(NaN));
// => true
isNaN(undefined);
// => true
_.isNaN(undefined);
// => false
Checks if value
is a native function.
value
(*): The value to check.
(boolean): Returns true
if value
is a native function, else false
.
_.isNative(Array.prototype.push);
// => true
_.isNative(_);
// => false
Checks if value
is null
or undefined
.
value
(*): The value to check.
(boolean): Returns true
if value
is nullish, else false
.
_.isNil(null);
// => true
_.isNil(void 0);
// => true
_.isNil(NaN);
// => false
Checks if value
is null
.
value
(*): The value to check.
(boolean): Returns true
if value
is null
, else false
.
_.isNull(null);
// => true
_.isNull(void 0);
// => false
Checks if value
is classified as a Number
primitive or object.
Note: To exclude Infinity
, -Infinity
, and NaN
, which are classified
as numbers, use the _.isFinite
method.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isNumber(3);
// => true
_.isNumber(Number.MIN_VALUE);
// => true
_.isNumber(Infinity);
// => true
_.isNumber('3');
// => false
Checks if value
is the language type of Object
.
(e.g. arrays, functions, objects, regexes, new Number(0)
, and new String('')
)
value
(*): The value to check.
(boolean): Returns true
if value
is an object, else false
.
_.isObject({});
// => true
_.isObject([1, 2, 3]);
// => true
_.isObject(_.noop);
// => true
_.isObject(null);
// => false
Checks if value
is object-like. A value is object-like if it's not null
and has a typeof
result of "object".
value
(*): The value to check.
(boolean): Returns true
if value
is object-like, else false
.
_.isObjectLike({});
// => true
_.isObjectLike([1, 2, 3]);
// => true
_.isObjectLike(_.noop);
// => false
_.isObjectLike(null);
// => false
Checks if value
is a plain object, that is, an object created by the
Object
constructor or one with a [[Prototype]]
of null
.
value
(*): The value to check.
(boolean): Returns true
if value
is a plain object, else false
.
function Foo() {
this.a = 1;
}
_.isPlainObject(new Foo);
// => false
_.isPlainObject([1, 2, 3]);
// => false
_.isPlainObject({ 'x': 0, 'y': 0 });
// => true
_.isPlainObject(Object.create(null));
// => true
Checks if value
is classified as a RegExp
object.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isRegExp(/abc/);
// => true
_.isRegExp('/abc/');
// => false
Checks if value
is a safe integer. An integer is safe if it's an IEEE-754
double precision number which isn't the result of a rounded unsafe integer.
Note: This method is based on Number.isSafeInteger
.
value
(*): The value to check.
(boolean): Returns true
if value
is a safe integer, else false
.
_.isSafeInteger(3);
// => true
_.isSafeInteger(Number.MIN_VALUE);
// => false
_.isSafeInteger(Infinity);
// => false
_.isSafeInteger('3');
// => false
Checks if value
is classified as a String
primitive or object.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isString('abc');
// => true
_.isString(1);
// => false
Checks if value
is classified as a Symbol
primitive or object.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isSymbol(Symbol.iterator);
// => true
_.isSymbol('abc');
// => false
Checks if value
is classified as a typed array.
value
(*): The value to check.
(boolean): Returns true
if value
is correctly classified, else false
.
_.isTypedArray(new Uint8Array);
// => true
_.isTypedArray([]);
// => false
Checks if value
is undefined
.
value
(*): The value to check.
(boolean): Returns true
if value
is undefined
, else false
.
_.isUndefined(void 0);
// => true
_.isUndefined(null);
// => false
Checks if value
is less than other
.
other
(*): The other value to compare.value
(*): The value to compare.
(boolean): Returns true
if value
is less than other
, else false
.
_.lt(3, 1);
// => true
_.lt(3, 3);
// => false
_.lt(1, 3);
// => false
Checks if value
is less than or equal to other
.
other
(*): The other value to compare.value
(*): The value to compare.
(boolean): Returns true
if value
is less than or equal to other
, else false
.
_.lte(3, 1);
// => true
_.lte(3, 3);
// => true
_.lte(1, 3);
// => false
Converts value
to an array.
value
(*): The value to convert.
(Array): Returns the converted array.
_.toArray({ 'a': 1, 'b': 2 });
// => [1, 2]
_.toArray('abc');
// => ['a', 'b', 'c']
_.toArray(1);
// => []
_.toArray(null);
// => []
Converts value
to an integer.
Note: This function is loosely based on ToInteger
.
value
(*): The value to convert.
(number): Returns the converted integer.
_.toInteger(3);
// => 3
_.toInteger(Number.MIN_VALUE);
// => 0
_.toInteger(Infinity);
// => 1.7976931348623157e+308
_.toInteger('3');
// => 3
Converts value
to an integer suitable for use as the length of an
array-like object.
Note: This method is based on ToLength
.
value
(*): The value to convert.
(number): Returns the converted integer.
_.toLength(3);
// => 3
_.toLength(Number.MIN_VALUE);
// => 0
_.toLength(Infinity);
// => 4294967295
_.toLength('3');
// => 3
Converts value
to a number.
value
(*): The value to process.
(number): Returns the number.
_.toNumber(3);
// => 3
_.toNumber(Number.MIN_VALUE);
// => 5e-324
_.toNumber(Infinity);
// => Infinity
_.toNumber('3');
// => 3
Converts value
to a plain object flattening inherited enumerable
properties of value
to own properties of the plain object.
value
(*): The value to convert.
(Object): Returns the converted plain object.
function Foo() {
this.b = 2;
}
Foo.prototype.c = 3;
_.assign({ 'a': 1 }, new Foo);
// => { 'a': 1, 'b': 2 }
_.assign({ 'a': 1 }, _.toPlainObject(new Foo));
// => { 'a': 1, 'b': 2, 'c': 3 }
Converts value
to a safe integer. A safe integer can be compared and
represented correctly.
value
(*): The value to convert.
(number): Returns the converted integer.
_.toSafeInteger(3);
// => 3
_.toSafeInteger(Number.MIN_VALUE);
// => 0
_.toSafeInteger(Infinity);
// => 9007199254740991
_.toSafeInteger('3');
// => 3
Converts value
to a string if it's not one. An empty string is returned
for null
and undefined
values. The sign of -0
is preserved.
value
(*): The value to process.
(string): Returns the string.
_.toString(null);
// => ''
_.toString(-0);
// => '-0'
_.toString([1, 2, 3]);
// => '1,2,3'
Adds two numbers.
augend
(number): The first number in an addition.addend
(number): The second number in an addition.
(number): Returns the total.
_.add(6, 4);
// => 10
Computes number
rounded up to precision
.
[precision=0]
(number): The precision to round up to.number
(number): The number to round up.
(number): Returns the rounded up number.
_.ceil(4.006);
// => 5
_.ceil(2, 6.004);
// => 6.01
_.ceil(-2, 6040);
// => 6100
Computes number
rounded down to precision
.
[precision=0]
(number): The precision to round down to.number
(number): The number to round down.
(number): Returns the rounded down number.
_.floor(4.006);
// => 4
_.floor(2, 0.046);
// => 0.04
_.floor(-2, 4060);
// => 4000
Computes the maximum value of array
. If array
is empty or falsey
undefined
is returned.
array
(Array): The array to iterate over.
(*): Returns the maximum value.
_.max([4, 2, 8, 6]);
// => 8
_.max([]);
// => undefined
This method is like _.max
except that it accepts iteratee
which is
invoked for each element in array
to generate the criterion by which
the value is ranked. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.array
(Array): The array to iterate over.
(*): Returns the maximum value.
var objects = [{ 'n': 1 }, { 'n': 2 }];
_.maxBy(function(o) { return o.n; }, objects);
// => { 'n': 2 }
// The `_.property` iteratee shorthand.
_.maxBy('n', objects);
// => { 'n': 2 }
Computes the mean of the values in array
.
array
(Array): The array to iterate over.
(number): Returns the mean.
_.mean([4, 2, 8, 6]);
// => 5
Computes the minimum value of array
. If array
is empty or falsey
undefined
is returned.
array
(Array): The array to iterate over.
(*): Returns the minimum value.
_.min([4, 2, 8, 6]);
// => 2
_.min([]);
// => undefined
This method is like _.min
except that it accepts iteratee
which is
invoked for each element in array
to generate the criterion by which
the value is ranked. The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.array
(Array): The array to iterate over.
(*): Returns the minimum value.
var objects = [{ 'n': 1 }, { 'n': 2 }];
_.minBy(function(o) { return o.n; }, objects);
// => { 'n': 1 }
// The `_.property` iteratee shorthand.
_.minBy('n', objects);
// => { 'n': 1 }
Computes number
rounded to precision
.
[precision=0]
(number): The precision to round to.number
(number): The number to round.
(number): Returns the rounded number.
_.round(4.006);
// => 4
_.round(2, 4.006);
// => 4.01
_.round(-2, 4060);
// => 4100
Subtract two numbers.
minuend
(number): The first number in a subtraction.subtrahend
(number): The second number in a subtraction.
(number): Returns the difference.
_.subtract(6, 4);
// => 2
Computes the sum of the values in array
.
array
(Array): The array to iterate over.
(number): Returns the sum.
_.sum([4, 2, 8, 6]);
// => 20
This method is like _.sum
except that it accepts iteratee
which is
invoked for each element in array
to generate the value to be summed.
The iteratee is invoked with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.array
(Array): The array to iterate over.
(number): Returns the sum.
var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];
_.sumBy(function(o) { return o.n; }, objects);
// => 20
// The `_.property` iteratee shorthand.
_.sumBy('n', objects);
// => 20
Clamps number
within the inclusive lower
and upper
bounds.
[lower]
(number): The lower bound.upper
(number): The upper bound.number
(number): The number to clamp.
(number): Returns the clamped number.
_.clamp(-5, 5, -10);
// => -5
_.clamp(-5, 5, 10);
// => 5
Checks if n
is between start
and up to but not including, end
. If
end
is not specified it's set to start
with start
then set to 0
.
If start
is greater than end
the params are swapped to support
negative ranges.
end
(number): The end of the range.[start=0]
(number): The start of the range.number
(number): The number to check.
(boolean): Returns true
if number
is in the range, else false
.
_.inRange(4, 2, 3);
// => true
_.inRange(8, 4);
// => true
_.inRange(2, 4);
// => false
_.inRange(2, 2);
// => false
_.inRange(2, 1.2);
// => true
_.inRange(4, 5.2);
// => false
_.inRange(-6, -2, -3);
// => true
Produces a random number between the inclusive lower
and upper
bounds.
If only one argument is provided a number between 0
and the given number
is returned. If floating
is true
, or either lower
or upper
are floats,
a floating-point number is returned instead of an integer.
Note: JavaScript follows the IEEE-754 standard for resolving
floating-point values which can produce unexpected results.
[lower=0]
(number): The lower bound.[upper=1]
(number): The upper bound.[floating]
(boolean): Specify returning a floating-point number.
(number): Returns the random number.
_.random(0, 5);
// => an integer between 0 and 5
_.random(5);
// => also an integer between 0 and 5
_.random(5, true);
// => a floating-point number between 0 and 5
_.random(1.2, 5.2);
// => a floating-point number between 1.2 and 5.2
Assigns own enumerable properties of source objects to the destination
object. Source objects are applied from left to right. Subsequent sources
overwrite property assignments of previous sources.
Note: This method mutates object
and is loosely based on
Object.assign
.
object
(Object): The destination object.[sources]
(...Object): The source objects.
(Object): Returns object
.
function Foo() {
this.c = 3;
}
function Bar() {
this.e = 5;
}
Foo.prototype.d = 4;
Bar.prototype.f = 6;
_.assign({ 'a': 1 }, new Foo, new Bar);
// => { 'a': 1, 'c': 3, 'e': 5 }
This method is like _.assign
except that it iterates over own and
inherited source properties.
Note: This method mutates object
.
_.extend
object
(Object): The destination object.[sources]
(...Object): The source objects.
(Object): Returns object
.
function Foo() {
this.b = 2;
}
function Bar() {
this.d = 4;
}
Foo.prototype.c = 3;
Bar.prototype.e = 5;
_.assignIn({ 'a': 1 }, new Foo, new Bar);
// => { 'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5 }
This method is like _.assignIn
except that it accepts customizer
which
is invoked to produce the assigned values. If customizer
returns undefined
assignment is handled by the method instead. The customizer
is invoked
with five arguments: (objValue, srcValue, key, object, source).
Note: This method mutates object
.
_.extendWith
[customizer]
(Function): The function to customize assigned values.object
(Object): The destination object.sources
(...Object): The source objects.
(Object): Returns object
.
function customizer(objValue, srcValue) {
return _.isUndefined(objValue) ? srcValue : objValue;
}
var defaults = _.partialRight(_.assignInWith, customizer);
defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }
This method is like _.assign
except that it accepts customizer
which
is invoked to produce the assigned values. If customizer
returns undefined
assignment is handled by the method instead. The customizer
is invoked
with five arguments: (objValue, srcValue, key, object, source).
Note: This method mutates object
.
[customizer]
(Function): The function to customize assigned values.object
(Object): The destination object.sources
(...Object): The source objects.
(Object): Returns object
.
function customizer(objValue, srcValue) {
return _.isUndefined(objValue) ? srcValue : objValue;
}
var defaults = _.partialRight(_.assignWith, customizer);
defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
// => { 'a': 1, 'b': 2 }
Creates an array of values corresponding to paths
of object
.
[paths]
(...(string|string[]): The property paths of elements to pick, specified individually or in arrays.object
(Object): The object to iterate over.
(Array): Returns the new array of picked elements.
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };
_.at(['a[0].b.c', 'a[1]'], object);
// => [3, 4]
_.at(2, 0, ['a', 'b', 'c']);
// => ['a', 'c']
Creates an object that inherits from the prototype
object. If a properties
object is provided its own enumerable properties are assigned to the created object.
[properties]
(Object): The properties to assign to the object.prototype
(Object): The object to inherit from.
(Object): Returns the new object.
function Shape() {
this.x = 0;
this.y = 0;
}
function Circle() {
Shape.call(this);
}
Circle.prototype = _.create({
'constructor': Circle
}, Shape.prototype);
var circle = new Circle;
circle instanceof Circle;
// => true
circle instanceof Shape;
// => true
Assigns own and inherited enumerable properties of source objects to the
destination object for all destination properties that resolve to undefined
.
Source objects are applied from left to right. Once a property is set,
additional values of the same property are ignored.
Note: This method mutates object
.
[sources]
(...Object): The source objects.object
(Object): The destination object.
(Object): Returns object
.
_.defaults({ 'user': 'fred' }, { 'age': 36 }, { 'user': 'barney' });
// => { 'user': 'barney', 'age': 36 }
This method is like _.defaults
except that it recursively assigns
default properties.
Note: This method mutates object
.
[sources]
(...Object): The source objects.object
(Object): The destination object.
(Object): Returns object
.
_.defaultsDeep(
{ 'user': { 'name': 'fred', 'age': 36 } },
{ 'user': { 'name': 'barney' } }
);
// => { 'user': { 'name': 'barney', 'age': 36 } }
This method is like _.find
except that it returns the key of the first
element predicate
returns truthy for instead of the element itself.
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.object
(Object): The object to search.
(string|undefined): Returns the key of the matched element, else undefined
.
var users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 1, 'active': true }
};
_.findKey(function(o) { return o.age < 40; }, users);
// => 'barney' (iteration order is not guaranteed)
// The `_.matches` iteratee shorthand.
_.findKey({ 'age': 1, 'active': true }, users);
// => 'pebbles'
// The `_.matchesProperty` iteratee shorthand.
_.findKey(['active', false], users);
// => 'fred'
// The `_.property` iteratee shorthand.
_.findKey('active', users);
// => 'barney'
This method is like _.findKey
except that it iterates over elements of
a collection in the opposite order.
[predicate=_.identity]
(Function|Object|string): The function invoked per iteration.object
(Object): The object to search.
(string|undefined): Returns the key of the matched element, else undefined
.
var users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 1, 'active': true }
};
_.findLastKey(function(o) { return o.age < 40; }, users);
// => returns 'pebbles' assuming `_.findKey` returns 'barney'
// The `_.matches` iteratee shorthand.
_.findLastKey({ 'age': 36, 'active': true }, users);
// => 'barney'
// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(['active', false], users);
// => 'fred'
// The `_.property` iteratee shorthand.
_.findLastKey('active', users);
// => 'pebbles'
Iterates over own and inherited enumerable properties of an object invoking
iteratee
for each property. The iteratee is invoked with three arguments:
(value, key, object). Iteratee functions may exit iteration early by explicitly
returning false
.
[iteratee=_.identity]
(Function): The function invoked per iteration.object
(Object): The object to iterate over.
(Object): Returns object
.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forIn(function(value, key) {
console.log(key);
}, new Foo);
// => logs 'a', 'b', then 'c' (iteration order is not guaranteed)
This method is like _.forIn
except that it iterates over properties of
object
in the opposite order.
[iteratee=_.identity]
(Function): The function invoked per iteration.object
(Object): The object to iterate over.
(Object): Returns object
.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forInRight(function(value, key) {
console.log(key);
}, new Foo);
// => logs 'c', 'b', then 'a' assuming `_.forIn` logs 'a', 'b', then 'c'
Iterates over own enumerable properties of an object invoking iteratee
for each property. The iteratee is invoked with three arguments:
(value, key, object). Iteratee functions may exit iteration early by
explicitly returning false
.
[iteratee=_.identity]
(Function): The function invoked per iteration.object
(Object): The object to iterate over.
(Object): Returns object
.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forOwn(function(value, key) {
console.log(key);
}, new Foo);
// => logs 'a' then 'b' (iteration order is not guaranteed)
This method is like _.forOwn
except that it iterates over properties of
object
in the opposite order.
[iteratee=_.identity]
(Function): The function invoked per iteration.object
(Object): The object to iterate over.
(Object): Returns object
.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.forOwnRight(function(value, key) {
console.log(key);
}, new Foo);
// => logs 'b' then 'a' assuming `_.forOwn` logs 'a' then 'b'
Creates an array of function property names from own enumerable properties
of object
.
object
(Object): The object to inspect.
(Array): Returns the new array of property names.
function Foo() {
this.a = _.constant('a');
this.b = _.constant('b');
}
Foo.prototype.c = _.constant('c');
_.functions(new Foo);
// => ['a', 'b']
Creates an array of function property names from own and inherited
enumerable properties of object
.
object
(Object): The object to inspect.
(Array): Returns the new array of property names.
function Foo() {
this.a = _.constant('a');
this.b = _.constant('b');
}
Foo.prototype.c = _.constant('c');
_.functionsIn(new Foo);
// => ['a', 'b', 'c']
Gets the value at path
of object
. If the resolved value is
undefined
the defaultValue
is used in its place.
[defaultValue]
(*): The value returned if the resolved value isundefined
.path
(Array|string): The path of the property to get.object
(Object): The object to query.
(*): Returns the resolved value.
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.get('a[0].b.c', object);
// => 3
_.get(['a', '0', 'b', 'c'], object);
// => 3
_.get('default', 'a.b.c', object);
// => 'default'
Checks if path
is a direct property of object
.
path
(Array|string): The path to check.object
(Object): The object to query.
(boolean): Returns true
if path
exists, else false
.
var object = { 'a': { 'b': { 'c': 3 } } };
var other = _.create({ 'a': _.create({ 'b': _.create({ 'c': 3 }) }) });
_.has('a', object);
// => true
_.has('a.b.c', object);
// => true
_.has(['a', 'b', 'c'], object);
// => true
_.has('a', other);
// => false
Checks if path
is a direct or inherited property of object
.
path
(Array|string): The path to check.object
(Object): The object to query.
(boolean): Returns true
if path
exists, else false
.
var object = _.create({ 'a': _.create({ 'b': _.create({ 'c': 3 }) }) });
_.hasIn('a', object);
// => true
_.hasIn('a.b.c', object);
// => true
_.hasIn(['a', 'b', 'c'], object);
// => true
_.hasIn('b', object);
// => false
Creates an object composed of the inverted keys and values of object
.
If object
contains duplicate values, subsequent values overwrite property
assignments of previous values.
object
(Object): The object to invert.
(Object): Returns the new inverted object.
var object = { 'a': 1, 'b': 2, 'c': 1 };
_.invert(object);
// => { '1': 'c', '2': 'b' }
This method is like _.invert
except that the inverted object is generated
from the results of running each element of object
through iteratee
.
The corresponding inverted value of each inverted key is an array of keys
responsible for generating the inverted value. The iteratee is invoked
with one argument: (value).
[iteratee=_.identity]
(Function|Object|string): The iteratee invoked per element.object
(Object): The object to invert.
(Object): Returns the new inverted object.
var object = { 'a': 1, 'b': 2, 'c': 1 };
_.invertBy(object);
// => { '1': ['a', 'c'], '2': ['b'] }
_.invertBy(function(value) {
return 'group' + value;
}, object);
// => { 'group1': ['a', 'c'], 'group2': ['b'] }
Invokes the method at path
of object
.
[args]
(...*): The arguments to invoke the method with.path
(Array|string): The path of the method to invoke.object
(Object): The object to query.
(*): Returns the result of the invoked method.
var object = { 'a': [{ 'b': { 'c': [1, 2, 3, 4] } }] };
_.invoke(1, 3, 'a[0].b.c.slice', object);
// => [2, 3]
Creates an array of the own enumerable property names of object
.
Note: Non-object values are coerced to objects. See the
ES spec
for more details.
object
(Object): The object to query.
(Array): Returns the array of property names.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.keys(new Foo);
// => ['a', 'b'] (iteration order is not guaranteed)
_.keys('hi');
// => ['0', '1']
Creates an array of the own and inherited enumerable property names of object
.
Note: Non-object values are coerced to objects.
object
(Object): The object to query.
(Array): Returns the array of property names.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.keysIn(new Foo);
// => ['a', 'b', 'c'] (iteration order is not guaranteed)
The opposite of _.mapValues
; this method creates an object with the
same values as object
and keys generated by running each own enumerable
property of object
through iteratee
.
[iteratee=_.identity]
(Function|Object|string): The function invoked per iteration.object
(Object): The object to iterate over.
(Object): Returns the new mapped object.
_.mapKeys(function(value, key) {
return key + value;
}, { 'a': 1, 'b': 2 });
// => { 'a1': 1, 'b2': 2 }
Creates an object with the same keys as object
and values generated by
running each own enumerable property of object
through iteratee
. The
iteratee function is invoked with three arguments: (value, key, object).
[iteratee=_.identity]
(Function|Object|string): The function invoked per iteration.object
(Object): The object to iterate over.
(Object): Returns the new mapped object.
var users = {
'fred': { 'user': 'fred', 'age': 40 },
'pebbles': { 'user': 'pebbles', 'age': 1 }
};
_.mapValues(function(o) { return o.age; }, users);
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
// The `_.property` iteratee shorthand.
_.mapValues('age', users);
// => { 'fred': 40, 'pebbles': 1 } (iteration order is not guaranteed)
Recursively merges own and inherited enumerable properties of source
objects into the destination object, skipping source properties that resolve
to undefined
. Array and plain object properties are merged recursively.
Other objects and value types are overridden by assignment. Source objects
are applied from left to right. Subsequent sources overwrite property
assignments of previous sources.
Note: This method mutates object
.
object
(Object): The destination object.[sources]
(...Object): The source objects.
(Object): Returns object
.
var users = {
'data': [{ 'user': 'barney' }, { 'user': 'fred' }]
};
var ages = {
'data': [{ 'age': 36 }, { 'age': 40 }]
};
_.merge(users, ages);
// => { 'data': [{ 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }] }
This method is like _.merge
except that it accepts customizer
which
is invoked to produce the merged values of the destination and source
properties. If customizer
returns undefined
merging is handled by the
method instead. The customizer
is invoked with seven arguments:
(objValue, srcValue, key, object, source, stack).
Note: This method mutates object
.
customizer
(Function): The function to customize assigned values.object
(Object): The destination object.sources
(...Object): The source objects.
(Object): Returns object
.
function customizer(objValue, srcValue) {
if (_.isArray(objValue)) {
return objValue.concat(srcValue);
}
}
var object = {
'fruits': ['apple'],
'vegetables': ['beet']
};
var other = {
'fruits': ['banana'],
'vegetables': ['carrot']
};
_.mergeWith(customizer, object, other);
// => { 'fruits': ['apple', 'banana'], 'vegetables': ['beet', 'carrot'] }
The opposite of _.pick
; this method creates an object composed of the
own and inherited enumerable properties of object
that are not omitted.
[props]
(...(string|string[]): The property names to omit, specified individually or in arrays..object
(Object): The source object.
(Object): Returns the new object.
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.omit(['a', 'c'], object);
// => { 'b': '2' }
The opposite of _.pickBy
; this method creates an object composed of the
own and inherited enumerable properties of object
that predicate
doesn't return truthy for.
[predicate=_.identity]
(Function|Object|string): The function invoked per property.object
(Object): The source object.
(Object): Returns the new object.
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.omitBy(_.isNumber, object);
// => { 'b': '2' }
Creates an object composed of the picked object
properties.
[props]
(...(string|string[]): The property names to pick, specified individually or in arrays.object
(Object): The source object.
(Object): Returns the new object.
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.pick(['a', 'c'], object);
// => { 'a': 1, 'c': 3 }
Creates an object composed of the object
properties predicate
returns
truthy for. The predicate is invoked with two arguments: (value, key).
[predicate=_.identity]
(Function|Object|string): The function invoked per property.object
(Object): The source object.
(Object): Returns the new object.
var object = { 'a': 1, 'b': '2', 'c': 3 };
_.pickBy(_.isNumber, object);
// => { 'a': 1, 'c': 3 }
This method is like _.get
except that if the resolved value is a function
it's invoked with the this
binding of its parent object and its result
is returned.
[defaultValue]
(*): The value returned if the resolved value isundefined
.path
(Array|string): The path of the property to resolve.object
(Object): The object to query.
(*): Returns the resolved value.
var object = { 'a': [{ 'b': { 'c1': 3, 'c2': _.constant(4) } }] };
_.result('a[0].b.c1', object);
// => 3
_.result('a[0].b.c2', object);
// => 4
_.result('default', 'a[0].b.c3', object);
// => 'default'
_.result(_.constant('default'), 'a[0].b.c3', object);
// => 'default'
Sets the value at path
of object
. If a portion of path
doesn't exist
it's created. Arrays are created for missing index properties while objects
are created for all other missing properties. Use _.setWith
to customize
path
creation.
Note: This method mutates object
.
path
(Array|string): The path of the property to set.value
(*): The value to set.object
(Object): The object to modify.
(Object): Returns object
.
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.set('a[0].b.c', 4, object);
console.log(object.a[0].b.c);
// => 4
_.set('x[0].y.z', 5, object);
console.log(object.x[0].y.z);
// => 5
This method is like _.set
except that it accepts customizer
which is
invoked to produce the objects of path
. If customizer
returns undefined
path creation is handled by the method instead. The customizer
is invoked
with three arguments: (nsValue, key, nsObject).
Note: This method mutates object
.
[customizer]
(Function): The function to customize assigned values.path
(Array|string): The path of the property to set.value
(*): The value to set.object
(Object): The object to modify.
(Object): Returns object
.
_.setWith(Object, '[0][1][2]', 3, { '0': { 'length': 2 } });
// => { '0': { '1': { '2': 3 }, 'length': 2 } }
Creates an array of own enumerable key-value pairs for object
.
object
(Object): The object to query.
(Array): Returns the new array of key-value pairs.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.toPairs(new Foo);
// => [['a', 1], ['b', 2]] (iteration order is not guaranteed)
Creates an array of own and inherited enumerable key-value pairs for object
.
object
(Object): The object to query.
(Array): Returns the new array of key-value pairs.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.toPairsIn(new Foo);
// => [['a', 1], ['b', 2], ['c', 1]] (iteration order is not guaranteed)
An alternative to _.reduce
; this method transforms object
to a new
accumulator
object which is the result of running each of its own enumerable
properties through iteratee
, with each invocation potentially mutating
the accumulator
object. The iteratee is invoked with four arguments:
(accumulator, value, key, object). Iteratee functions may exit iteration
early by explicitly returning false
.
[iteratee=_.identity]
(Function): The function invoked per iteration.[accumulator]
(*): The custom accumulator value.object
(Array|Object): The object to iterate over.
(*): Returns the accumulated value.
_.transform(function(result, n) {
result.push(n *= n);
return n % 2 == 0;
}, [], [2, 3, 4]);
// => [4, 9]
_.transform(function(result, value, key) {
(result[value] || (result[value] = [])).push(key);
}, {}, { 'a': 1, 'b': 2, 'c': 1 });
// => { '1': ['a', 'c'], '2': ['b'] }
Removes the property at path
of object
.
Note: This method mutates object
.
path
(Array|string): The path of the property to unset.object
(Object): The object to modify.
(boolean): Returns true
if the property is deleted, else false
.
var object = { 'a': [{ 'b': { 'c': 7 } }] };
_.unset('a[0].b.c', object);
// => true
console.log(object);
// => { 'a': [{ 'b': {} }] };
_.unset('a[0].b.c', object);
// => true
console.log(object);
// => { 'a': [{ 'b': {} }] };
Creates an array of the own enumerable property values of object
.
Note: Non-object values are coerced to objects.
object
(Object): The object to query.
(Array): Returns the array of property values.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.values(new Foo);
// => [1, 2] (iteration order is not guaranteed)
_.values('hi');
// => ['h', 'i']
Creates an array of the own and inherited enumerable property values of object
.
Note: Non-object values are coerced to objects.
object
(Object): The object to query.
(Array): Returns the array of property values.
function Foo() {
this.a = 1;
this.b = 2;
}
Foo.prototype.c = 3;
_.valuesIn(new Foo);
// => [1, 2, 3] (iteration order is not guaranteed)
Creates a lodash
object which wraps value
to enable implicit method
chaining. Methods that operate on and return arrays, collections, and
functions can be chained together. Methods that retrieve a single value or
may return a primitive value will automatically end the chain sequence and
return the unwrapped value. Otherwise, the value must be unwrapped with
_#value
.
Explicit chaining, which must be unwrapped with _#value
in all cases,
may be enabled using _.chain
.
The execution of chained methods is lazy, that is, it's deferred until
_#value
is implicitly or explicitly called.
Lazy evaluation allows several methods to support shortcut fusion. Shortcut
fusion is an optimization to merge iteratee calls; this avoids the creation
of intermediate arrays and can greatly reduce the number of iteratee executions.
Sections of a chain sequence qualify for shortcut fusion if the section is
applied to an array of at least two hundred elements and any iteratees
accept only one argument. The heuristic for whether a section qualifies
for shortcut fusion is subject to change.
Chaining is supported in custom builds as long as the _#value
method is
directly or indirectly included in the build.
In addition to lodash methods, wrappers have Array
and String
methods.
The wrapper Array
methods are:
concat
, join
, pop
, push
, shift
, sort
, splice
, and unshift
The wrapper String
methods are:
replace
and split
The wrapper methods that support shortcut fusion are:
at
, compact
, drop
, dropRight
, dropWhile
, filter
, find
,
findLast
, head
, initial
, last
, map
, reject
, reverse
, slice
,
tail
, take
, takeRight
, takeRightWhile
, takeWhile
, and toArray
The chainable wrapper methods are:
after
, ary
, assign
, assignIn
, assignInWith
, assignWith
,
at
, before
, bind
, bindAll
, bindKey
, chain
, chunk
, commit
,
compact
, concat
, conforms
, constant
, countBy
, create
, curry
,
debounce
, defaults
, defaultsDeep
, defer
, delay
, difference
,
differenceBy
, differenceWith
, drop
, dropRight
, dropRightWhile
,
dropWhile
, fill
, filter
, flatten
, flattenDeep
, flip
, flow
,
flowRight
, fromPairs
, functions
, functionsIn
, groupBy
, initial
,
intersection
, intersectionBy
, intersectionWith
, invert
, invertBy
,
invokeMap
, iteratee
, keyBy
, keys
, keysIn
, map
, mapKeys
,
mapValues
, matches
, matchesProperty
, memoize
, merge
, mergeWith
,
method
, methodOf
, mixin
, negate
, nthArg
, omit
, omitBy
, once
,
orderBy
, over
, overArgs
, overEvery
, overSome
, partial
,
partialRight
, partition
, pick
, pickBy
, plant
, property
,
propertyOf
, pull
, pullAll
, pullAllBy
, pullAt
, push
, range
,
rangeRight
, rearg
, reject
, remove
, rest
, reverse
, sampleSize
,
set
, setWith
, shuffle
, slice
, sort
, sortBy
, splice
, spread
,
tail
, take
, takeRight
, takeRightWhile
, takeWhile
, tap
, throttle
,
thru
, toArray
, toPairs
, toPairsIn
, toPath
, toPlainObject
,
transform
, unary
, union
, unionBy
, unionWith
, uniq
, uniqBy
,
uniqWith
, unset
, unshift
, unzip
, unzipWith
, values
, valuesIn
,
without
, wrap
, xor
, xorBy
, xorWith
, zip
, zipObject
,
zipObjectDeep
, and zipWith
The wrapper methods that are not chainable by default are:
add
, attempt
, camelCase
, capitalize
, ceil
, clamp
, clone
,
cloneDeep
, cloneDeepWith
, cloneWith
, deburr
, endsWith
, eq
,
escape
, escapeRegExp
, every
, find
, findIndex
, findKey
,
findLast
, findLastIndex
, findLastKey
, floor
, forEach
, forEachRight
,
forIn
, forInRight
, forOwn
, forOwnRight
, get
, gt
, gte
, has
,
hasIn
, head
, identity
, includes
, indexOf
, inRange
, invoke
,
isArguments
, isArray
, isArrayLike
, isArrayLikeObject
, isBoolean
,
isDate
, isElement
, isEmpty
, isEqual
, isEqualWith
, isError
,
isFinite
, isFunction
, isInteger
, isLength
, isMatch
, isMatchWith
,
isNaN
, isNative
, isNil
, isNull
, isNumber
, isObject
, isObjectLike
,
isPlainObject
, isRegExp
, isSafeInteger
, isString
, isUndefined
,
isTypedArray
, join
, kebabCase
, last
, lastIndexOf
, lowerCase
,
lowerFirst
, lt
, lte
, max
, maxBy
, mean
, min
, minBy
,
noConflict
, noop
, now
, pad
, padEnd
, padStart
, parseInt
,
pop
, random
, reduce
, reduceRight
, repeat
, result
, round
,
runInContext
, sample
, shift
, size
, snakeCase
, some
, sortedIndex
,
sortedIndexBy
, sortedLastIndex
, sortedLastIndexBy
, startCase
,
startsWith
, subtract
, sum
, sumBy
, template
, times
, toLower
,
toInteger
, toLength
, toNumber
, toSafeInteger
, toString
, toUpper
,
trim
, trimEnd
, trimStart
, truncate
, unescape
, uniqueId
,
upperCase
, upperFirst
, value
, and words
value
(*): The value to wrap in alodash
instance.
(Object): Returns the new lodash
wrapper instance.
function square(n) {
return n * n;
}
var wrapped = _([1, 2, 3]);
// Returns an unwrapped value.
wrapped.reduce(_.add);
// => 6
// Returns a wrapped value.
var squares = wrapped.map(square);
_.isArray(squares);
// => false
_.isArray(squares.value());
// => true
Creates a lodash
object that wraps value
with explicit method chaining enabled.
The result of such method chaining must be unwrapped with _#value
.
value
(*): The value to wrap.
(Object): Returns the new lodash
wrapper instance.
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 },
{ 'user': 'pebbles', 'age': 1 }
];
var youngest = _
.chain(users)
.sortBy('age')
.map(function(o) {
return o.user + ' is ' + o.age;
})
.head()
.value();
// => 'pebbles is 1'
This method invokes interceptor
and returns value
. The interceptor
is invoked with one argument; (value). The purpose of this method is to
"tap into" a method chain in order to modify intermediate results.
interceptor
(Function): The function to invoke.value
(*): The value to provide tointerceptor
.
(*): Returns value
.
_([1, 2, 3])
.tap(function(array) {
// Mutate input array.
array.pop();
})
.reverse()
.value();
// => [2, 1]
This method is like _.tap
except that it returns the result of interceptor
.
The purpose of this method is to "pass thru" values replacing intermediate
results in a method chain.
interceptor
(Function): The function to invoke.value
(*): The value to provide tointerceptor
.
(*): Returns the result of interceptor
.
_(' abc ')
.chain()
.trim()
.thru(function(value) {
return [value];
})
.value();
// => ['abc']
Enables the wrapper to be iterable.
(Object): Returns the wrapper object.
var wrapped = _([1, 2]);
wrapped[Symbol.iterator]() === wrapped;
// => true
Array.from(wrapped);
// => [1, 2]
This method is the wrapper version of _.at
.
[paths]
(...(string|string[]): The property paths of elements to pick, specified individually or in arrays.
(Object): Returns the new lodash
wrapper instance.
var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };
_(object).at(['a[0].b.c', 'a[1]']).value();
// => [3, 4]
_(['a', 'b', 'c']).at(0, 2).value();
// => ['a', 'c']
Enables explicit method chaining on the wrapper object.
(Object): Returns the new lodash
wrapper instance.
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 }
];
// A sequence without explicit chaining.
_(users).head();
// => { 'user': 'barney', 'age': 36 }
// A sequence with explicit chaining.
_(users)
.chain()
.head()
.pick('user')
.value();
// => { 'user': 'barney' }
Executes the chained sequence and returns the wrapped result.
(Object): Returns the new lodash
wrapper instance.
var array = [1, 2];
var wrapped = _(array).push(3);
console.log(array);
// => [1, 2]
wrapped = wrapped.commit();
console.log(array);
// => [1, 2, 3]
wrapped.last();
// => 3
console.log(array);
// => [1, 2, 3]
This method is the wrapper version of _.flatMap
.
[iteratee=_.identity]
(Function|Object|string): The function invoked per iteration.
(Object): Returns the new lodash
wrapper instance.
function duplicate(n) {
return [n, n];
}
_([1, 2]).flatMap(duplicate).value();
// => [1, 1, 2, 2]
Gets the next value on a wrapped object following the iterator protocol.
(Object): Returns the next iterator value.
var wrapped = _([1, 2]);
wrapped.next();
// => { 'done': false, 'value': 1 }
wrapped.next();
// => { 'done': false, 'value': 2 }
wrapped.next();
// => { 'done': true, 'value': undefined }
Creates a clone of the chained sequence planting value
as the wrapped value.
value
(*): The value to plant.
(Object): Returns the new lodash
wrapper instance.
function square(n) {
return n * n;
}
var wrapped = _([1, 2]).map(square);
var other = wrapped.plant([3, 4]);
other.value();
// => [9, 16]
wrapped.value();
// => [1, 4]
This method is the wrapper version of _.reverse
.
Note: This method mutates the wrapped array.
(Object): Returns the new lodash
wrapper instance.
var array = [1, 2, 3];
_(array).reverse().value()
// => [3, 2, 1]
console.log(array);
// => [3, 2, 1]
Executes the chained sequence to extract the unwrapped value.
_.prototype.toJSON, _.prototype.valueOf
(*): Returns the resolved unwrapped value.
_([1, 2, 3]).value();
// => [1, 2, 3]
Converts string
to camel case.
[string='']
(string): The string to convert.
(string): Returns the camel cased string.
_.camelCase('Foo Bar');
// => 'fooBar'
_.camelCase('--foo-bar');
// => 'fooBar'
_.camelCase('__foo_bar__');
// => 'fooBar'
Converts the first character of string
to upper case and the remaining
to lower case.
[string='']
(string): The string to capitalize.
(string): Returns the capitalized string.
_.capitalize('FRED');
// => 'Fred'
Deburrs string
by converting latin-1 supplementary letters
to basic latin letters and removing combining diacritical marks.
[string='']
(string): The string to deburr.
(string): Returns the deburred string.
_.deburr('déjà vu');
// => 'deja vu'
Checks if string
ends with the given target string.
[position=string.length]
(number): The position to search from.[target]
(string): The string to search for.[string='']
(string): The string to search.
(boolean): Returns true
if string
ends with target
, else false
.
_.endsWith('c', 'abc');
// => true
_.endsWith('b', 'abc');
// => false
_.endsWith(2, 'b', 'abc');
// => true
Converts the characters "&", "<", ">", '"', "'", and "`" in string
to
their corresponding HTML entities.
Note: No other characters are escaped. To escape additional
characters use a third-party library like he.
Though the ">" character is escaped for symmetry, characters like
">" and "/" don't need escaping in HTML and have no special meaning
unless they're part of a tag or unquoted attribute value.
See Mathias Bynens's article
(under "semi-related fun fact") for more details.
Backticks are escaped because in IE < 9, they can break out of
attribute values or HTML comments. See #59,
#102, #108, and
#133 of the HTML5 Security Cheatsheet
for more details.
When working with HTML you should always quote attribute values
to reduce XSS vectors.
[string='']
(string): The string to escape.
(string): Returns the escaped string.
_.escape('fred, barney, & pebbles');
// => 'fred, barney, & pebbles'
Escapes the RegExp
special characters "^", "$", "", ".", "*", "+",
"?", "(", ")", "[", "]", "{", "}", and "|" in string
.
[string='']
(string): The string to escape.
(string): Returns the escaped string.
_.escapeRegExp('[lodash](https://lodash.com/)');
// => '\[lodash\]\(https://lodash\.com/\)'
Converts string
to kebab case.
[string='']
(string): The string to convert.
(string): Returns the kebab cased string.
_.kebabCase('Foo Bar');
// => 'foo-bar'
_.kebabCase('fooBar');
// => 'foo-bar'
_.kebabCase('__foo_bar__');
// => 'foo-bar'
Converts string
, as space separated words, to lower case.
[string='']
(string): The string to convert.
(string): Returns the lower cased string.
_.lowerCase('--Foo-Bar');
// => 'foo bar'
_.lowerCase('fooBar');
// => 'foo bar'
_.lowerCase('__FOO_BAR__');
// => 'foo bar'
Converts the first character of string
to lower case.
[string='']
(string): The string to convert.
(string): Returns the converted string.
_.lowerFirst('Fred');
// => 'fred'
_.lowerFirst('FRED');
// => 'fRED'
Pads string
on the left and right sides if it's shorter than length
.
Padding characters are truncated if they can't be evenly divided by length
.
[chars=' ']
(string): The string used as padding.[length=0]
(number): The padding length.[string='']
(string): The string to pad.
(string): Returns the padded string.
_.pad(8, 'abc');
// => ' abc '
_.pad('_-', 8, 'abc');
// => '_-abc_-_'
_.pad(3, 'abc');
// => 'abc'
Pads string
on the right side if it's shorter than length
. Padding
characters are truncated if they exceed length
.
[chars=' ']
(string): The string used as padding.[length=0]
(number): The padding length.[string='']
(string): The string to pad.
(string): Returns the padded string.
_.padEnd(6, 'abc');
// => 'abc '
_.padEnd('_-', 6, 'abc');
// => 'abc_-_'
_.padEnd(3, 'abc');
// => 'abc'
Pads string
on the left side if it's shorter than length
. Padding
characters are truncated if they exceed length
.
[chars=' ']
(string): The string used as padding.[length=0]
(number): The padding length.[string='']
(string): The string to pad.
(string): Returns the padded string.
_.padStart(6, 'abc');
// => ' abc'
_.padStart('_-', 6, 'abc');
// => '_-_abc'
_.padStart(3, 'abc');
// => 'abc'
Converts string
to an integer of the specified radix. If radix
is
undefined
or 0
, a radix
of 10
is used unless value
is a hexadecimal,
in which case a radix
of 16
is used.
Note: This method aligns with the ES5 implementation
of parseInt
.
[radix]
(number): The radix to interpretvalue
by.string
(string): The string to convert.
(number): Returns the converted integer.
_.parseInt('08');
// => 8
_.map(_.parseInt, ['6', '08', '10']);
// => [6, 8, 10]
Repeats the given string n
times.
[n=0]
(number): The number of times to repeat the string.[string='']
(string): The string to repeat.
(string): Returns the repeated string.
_.repeat(3, '*');
// => '***'
_.repeat(2, 'abc');
// => 'abcabc'
_.repeat(0, 'abc');
// => ''
Replaces matches for pattern
in string
with replacement
.
Note: This method is based on String#replace
.
replacement
(Function|string): The match replacement.pattern
(RegExp|string): The pattern to replace.[string='']
(string): The string to modify.
(string): Returns the modified string.
_.replace('Barney', 'Fred', 'Hi Fred');
// => 'Hi Barney'
Converts string
to snake case.
[string='']
(string): The string to convert.
(string): Returns the snake cased string.
_.snakeCase('Foo Bar');
// => 'foo_bar'
_.snakeCase('fooBar');
// => 'foo_bar'
_.snakeCase('--foo-bar');
// => 'foo_bar'
Splits string
by separator
.
Note: This method is based on String#split
.
[limit]
(number): The length to truncate results to.separator
(RegExp|string): The separator pattern to split by.[string='']
(string): The string to split.
(Array): Returns the new array of string segments.
_.split(2, '-', 'a-b-c');
// => ['a', 'b']
Converts string
to start case.
[string='']
(string): The string to convert.
(string): Returns the start cased string.
_.startCase('--foo-bar');
// => 'Foo Bar'
_.startCase('fooBar');
// => 'Foo Bar'
_.startCase('__foo_bar__');
// => 'Foo Bar'
Checks if string
starts with the given target string.
[position=0]
(number): The position to search from.[target]
(string): The string to search for.[string='']
(string): The string to search.
(boolean): Returns true
if string
starts with target
, else false
.
_.startsWith('a', 'abc');
// => true
_.startsWith('b', 'abc');
// => false
_.startsWith(1, 'b', 'abc');
// => true
Creates a compiled template function that can interpolate data properties
in "interpolate" delimiters, HTML-escape interpolated data properties in
"escape" delimiters, and execute JavaScript in "evaluate" delimiters. Data
properties may be accessed as free variables in the template. If a setting
object is provided it takes precedence over _.templateSettings
values.
Note: In the development build _.template
utilizes
sourceURLs
for easier debugging.
For more information on precompiling templates see
lodash's custom builds documentation.
For more information on Chrome extension sandboxes see
Chrome's extensions documentation.
[string='']
(string): The template string.[options]
(Object): The options object.[options.escape]
(RegExp): The HTML "escape" delimiter.[options.evaluate]
(RegExp): The "evaluate" delimiter.[options.imports]
(Object): An object to import into the template as free variables.[options.interpolate]
(RegExp): The "interpolate" delimiter.[options.sourceURL]
(string): The sourceURL of the template's compiled source.[options.variable]
(string): The data object variable name.
(Function): Returns the compiled template function.
// Use the "interpolate" delimiter to create a compiled template.
var compiled = _.template('hello <%= user %>!');
compiled({ 'user': 'fred' });
// => 'hello fred!'
// Use the HTML "escape" delimiter to escape data property values.
var compiled = _.template('<b><%- value %></b>');
compiled({ 'value': '<script>' });
// => '<b><script></b>'
// Use the "evaluate" delimiter to execute JavaScript and generate HTML.
var compiled = _.template('<% _.forEach(users, function(user) { %><li><%- user %></li><% }); %>');
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'
// Use the internal `print` function in "evaluate" delimiters.
var compiled = _.template('<% print("hello " + user); %>!');
compiled({ 'user': 'barney' });
// => 'hello barney!'
// Use the ES delimiter as an alternative to the default "interpolate" delimiter.
var compiled = _.template('hello ${ user }!');
compiled({ 'user': 'pebbles' });
// => 'hello pebbles!'
// Use custom template delimiters.
_.templateSettings.interpolate = /{{([\s\S]+?)}}/g;
var compiled = _.template('hello {{ user }}!');
compiled({ 'user': 'mustache' });
// => 'hello mustache!'
// Use backslashes to treat delimiters as plain text.
var compiled = _.template('<%= "\\<%- value %\\>" %>');
compiled({ 'value': 'ignored' });
// => '<%- value %>'
// Use the `imports` option to import `jQuery` as `jq`.
var text = '<% jq.each(users, function(user) { %><li><%- user %></li><% }); %>';
var compiled = _.template({ 'imports': { 'jq': jQuery } }, text);
compiled({ 'users': ['fred', 'barney'] });
// => '<li>fred</li><li>barney</li>'
// Use the `sourceURL` option to specify a custom sourceURL for the template.
var compiled = _.template({ 'sourceURL': '/basic/greeting.jst' }, 'hello <%= user %>!');
compiled(data);
// => find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector
// Use the `variable` option to ensure a with-statement isn't used in the compiled template.
var compiled = _.template({ 'variable': 'data' }, 'hi <%= data.user %>!');
compiled.source;
// => function(data) {
// var __t, __p = '';
// __p += 'hi ' + ((__t = ( data.user )) == null ? '' : __t) + '!';
// return __p;
// }
// Use the `source` property to inline compiled templates for meaningful
// line numbers in error messages and stack traces.
fs.writeFileSync(path.join(cwd, 'jst.js'), '\
var JST = {\
"main": ' + _.template(mainText).source + '\
};\
');
Converts string
, as a whole, to lower case.
[string='']
(string): The string to convert.
(string): Returns the lower cased string.
_.toLower('--Foo-Bar');
// => '--foo-bar'
_.toLower('fooBar');
// => 'foobar'
_.toLower('__FOO_BAR__');
// => '__foo_bar__'
Converts string
, as a whole, to upper case.
[string='']
(string): The string to convert.
(string): Returns the upper cased string.
_.toUpper('--foo-bar');
// => '--FOO-BAR'
_.toUpper('fooBar');
// => 'FOOBAR'
_.toUpper('__foo_bar__');
// => '__FOO_BAR__'
Removes leading and trailing whitespace or specified characters from string
.
[chars=whitespace]
(string): The characters to trim.[string='']
(string): The string to trim.
(string): Returns the trimmed string.
_.trim(' abc ');
// => 'abc'
_.trim('_-', '-_-abc-_-');
// => 'abc'
_.map(_.trim, [' foo ', ' bar ']);
// => ['foo', 'bar']
Removes trailing whitespace or specified characters from string
.
[chars=whitespace]
(string): The characters to trim.[string='']
(string): The string to trim.
(string): Returns the trimmed string.
_.trimEnd(' abc ');
// => ' abc'
_.trimEnd('_-', '-_-abc-_-');
// => '-_-abc'
Removes leading whitespace or specified characters from string
.
[chars=whitespace]
(string): The characters to trim.[string='']
(string): The string to trim.
(string): Returns the trimmed string.
_.trimStart(' abc ');
// => 'abc '
_.trimStart('_-', '-_-abc-_-');
// => 'abc-_-'
Truncates string
if it's longer than the given maximum string length.
The last characters of the truncated string are replaced with the omission
string which defaults to "...".
[string='']
(string): The string to truncate.[options]
(Object): The options object.[options.length=30]
(number): The maximum string length.[options.omission='...']
(string): The string to indicate text is omitted.[options.separator]
(RegExp|string): The separator pattern to truncate to.
(string): Returns the truncated string.
_.truncate('hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there, neighbo...'
_.truncate({
'length': 24,
'separator': ' '
}, 'hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there,...'
_.truncate({
'length': 24,
'separator': /,? +/
}, 'hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there...'
_.truncate({
'omission': ' [...]'
}, 'hi-diddly-ho there, neighborino');
// => 'hi-diddly-ho there, neig [...]'
The inverse of _.escape
; this method converts the HTML entities
&
, <
, >
, "
, '
, and `
in string
to their
corresponding characters.
Note: No other HTML entities are unescaped. To unescape additional HTML
entities use a third-party library like he.
[string='']
(string): The string to unescape.
(string): Returns the unescaped string.
_.unescape('fred, barney, & pebbles');
// => 'fred, barney, & pebbles'
Converts string
, as space separated words, to upper case.
[string='']
(string): The string to convert.
(string): Returns the upper cased string.
_.upperCase('--foo-bar');
// => 'FOO BAR'
_.upperCase('fooBar');
// => 'FOO BAR'
_.upperCase('__foo_bar__');
// => 'FOO BAR'
Converts the first character of string
to upper case.
[string='']
(string): The string to convert.
(string): Returns the converted string.
_.upperFirst('fred');
// => 'Fred'
_.upperFirst('FRED');
// => 'FRED'
Splits string
into an array of its words.
[pattern]
(RegExp|string): The pattern to match words.[string='']
(string): The string to inspect.
(Array): Returns the words of string
.
_.words('fred, barney, & pebbles');
// => ['fred', 'barney', 'pebbles']
_.words(/[^, ]+/g, 'fred, barney, & pebbles');
// => ['fred', 'barney', '&', 'pebbles']
Attempts to invoke func
, returning either the result or the caught error
object. Any additional arguments are provided to func
when it's invoked.
func
(Function): The function to attempt.
(*): Returns the func
result or error object.
// Avoid throwing errors for invalid selectors.
var elements = _.attempt('>_>', function(selector) {
return document.querySelectorAll(selector);
});
if (_.isError(elements)) {
elements = [];
}
Binds methods of an object to the object itself, overwriting the existing
method.
Note: This method doesn't set the "length" property of bound functions.
methodNames
(...(string|string[]): The object method names to bind, specified individually or in arrays.object
(Object): The object to bind and assign the bound methods to.
(Object): Returns object
.
var view = {
'label': 'docs',
'onClick': function() {
console.log('clicked ' + this.label);
}
};
_.bindAll('onClick', view);
jQuery(element).on('click', view.onClick);
// => logs 'clicked docs' when clicked
Creates a function that iterates over pairs
invoking the corresponding
function of the first predicate to return truthy. The predicate-function
pairs are invoked with the this
binding and arguments of the created
function.
pairs
(Array): The predicate-function pairs.
(Function): Returns the new function.
var func = _.cond([
[_.matches({ 'a': 1 }), _.constant('matches A')],
[_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
[_.constant(true), _.constant('no match')]
]);
func({ 'a': 1, 'b': 2 });
// => 'matches A'
func({ 'a': 0, 'b': 1 });
// => 'matches B'
func({ 'a': '1', 'b': '2' });
// => 'no match'
Creates a function that invokes the predicate properties of source
with
the corresponding property values of a given object, returning true
if
all predicates return truthy, else false
.
source
(Object): The object of property predicates to conform to.
(Function): Returns the new function.
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 }
];
_.filter(_.conforms({ 'age': _.partial(_.gt, _, 38) }), users);
// => [{ 'user': 'fred', 'age': 40 }]
Creates a function that returns value
.
value
(*): The value to return from the new function.
(Function): Returns the new function.
var object = { 'user': 'fred' };
var getter = _.constant(object);
getter() === object;
// => true
Creates a function that returns the result of invoking the provided
functions with the this
binding of the created function, where each
successive invocation is supplied the return value of the previous.
[funcs]
(...(Function|Function[]): Functions to invoke.
(Function): Returns the new function.
function square(n) {
return n * n;
}
var addSquare = _.flow(square, _.add);
addSquare(1, 2);
// => 9
This method is like _.flow
except that it creates a function that
invokes the provided functions from right to left.
[funcs]
(...(Function|Function[]): Functions to invoke.
(Function): Returns the new function.
function square(n) {
return n * n;
}
var addSquare = _.flowRight(_.add, square);
addSquare(1, 2);
// => 9
This method returns the first argument provided to it.
value
(*): Any value.
(*): Returns value
.
var object = { 'user': 'fred' };
_.identity(object) === object;
// => true
Creates a function that invokes func
with the arguments of the created
function. If func
is a property name the created callback returns the
property value for a given element. If func
is an object the created
callback returns true
for elements that contain the equivalent object properties, otherwise it returns false
.
[func=_.identity]
(*): The value to convert to a callback.
(Function): Returns the callback.
var users = [
{ 'user': 'barney', 'age': 36 },
{ 'user': 'fred', 'age': 40 }
];
// Create custom iteratee shorthands.
_.iteratee = _.wrap(function(callback, func) {
var p = /^(\S+)\s*([<>])\s*(\S+)$/.exec(func);
return !p ? callback(func) : function(object) {
return (p[2] == '>' ? object[p[1]] > p[3] : object[p[1]] < p[3]);
};
}, _.iteratee);
_.filter('age > 36', users);
// => [{ 'user': 'fred', 'age': 40 }]
Creates a function that performs a deep partial comparison between a given
object and source
, returning true
if the given object has equivalent
property values, else false
.
Note: This method supports comparing the same values as _.isEqual
.
source
(Object): The object of property values to match.
(Function): Returns the new function.
var users = [
{ 'user': 'barney', 'age': 36, 'active': true },
{ 'user': 'fred', 'age': 40, 'active': false }
];
_.filter(_.matches({ 'age': 40, 'active': false }), users);
// => [{ 'user': 'fred', 'age': 40, 'active': false }]
Creates a function that performs a deep partial comparison between the
value at path
of a given object to srcValue
, returning true
if the
object value is equivalent, else false
.
Note: This method supports comparing the same values as _.isEqual
.
path
(Array|string): The path of the property to get.srcValue
(*): The value to match.
(Function): Returns the new function.
var users = [
{ 'user': 'barney' },
{ 'user': 'fred' }
];
_.find(_.matchesProperty('user', 'fred'), users);
// => { 'user': 'fred' }
Creates a function that invokes the method at path
of a given object.
Any additional arguments are provided to the invoked method.
[args]
(...*): The arguments to invoke the method with.path
(Array|string): The path of the method to invoke.
(Function): Returns the new function.
var objects = [
{ 'a': { 'b': { 'c': _.constant(2) } } },
{ 'a': { 'b': { 'c': _.constant(1) } } }
];
_.map(_.method('a.b.c'), objects);
// => [2, 1]
_.invokeMap('a.b.c', _.sortBy(objects, _.method(['a', 'b', 'c'])));
// => [1, 2]
The opposite of _.method
; this method creates a function that invokes
the method at a given path of object
. Any additional arguments are
provided to the invoked method.
[args]
(...*): The arguments to invoke the method with.object
(Object): The object to query.
(Function): Returns the new function.
var array = _.times(_.constant, 3),
object = { 'a': array, 'b': array, 'c': array };
_.map(_.methodOf(object), ['a[2]', 'c[0]']);
// => [2, 0]
_.map(_.methodOf(object), [['a', '2'], ['c', '0']]);
// => [2, 0]
Adds all own enumerable function properties of a source object to the
destination object. If object
is a function then methods are added to
its prototype as well.
Note: Use _.runInContext
to create a pristine lodash
function to
avoid conflicts caused by modifying the original.
[options]
(Object): The options object.[options.chain=true]
(boolean): Specify whether the functions added are chainable.source
(Object): The object of functions to add.[object=lodash]
(Function|Object): The destination object.
(Function|Object): Returns object
.
function vowels(string) {
return _.filter(function(v) {
return /[aeiou]/i.test(v);
}, string);
}
_.mixin({ 'vowels': vowels });
_.vowels('fred');
// => ['e']
_('fred').vowels().value();
// => ['e']
_.mixin({ 'chain': false }, { 'vowels': vowels });
_('fred').vowels();
// => ['e']
Reverts the _
variable to its previous value and returns a reference to
the lodash
function.
(Function): Returns the lodash
function.
var lodash = _.noConflict();
A no-operation function that returns undefined
regardless of the
arguments it receives.
var object = { 'user': 'fred' };
_.noop(object) === undefined;
// => true
Creates a function that returns its nth argument.
[n=0]
(number): The index of the argument to return.
(Function): Returns the new function.
var func = _.nthArg(1);
func('a', 'b', 'c');
// => 'b'
Creates a function that invokes iteratees
with the arguments provided
to the created function and returns their results.
iteratees
(...(Function|Function[]): The iteratees to invoke.
(Function): Returns the new function.
var func = _.over(Math.min, Math.max);
func(1, 2, 3, 4);
// => [4, 1]
Creates a function that checks if all of the predicates
return
truthy when invoked with the arguments provided to the created function.
predicates
(...(Function|Function[]): The predicates to check.
(Function): Returns the new function.
var func = _.overEvery(isFinite, Boolean);
func('1');
// => true
func(null);
// => false
func(NaN);
// => false
Creates a function that checks if any of the predicates
return
truthy when invoked with the arguments provided to the created function.
predicates
(...(Function|Function[]): The predicates to check.
(Function): Returns the new function.
var func = _.overSome(isFinite, Boolean);
func('1');
// => true
func(null);
// => true
func(NaN);
// => false
Creates a function that returns the value at path
of a given object.
path
(Array|string): The path of the property to get.
(Function): Returns the new function.
var objects = [
{ 'a': { 'b': { 'c': 2 } } },
{ 'a': { 'b': { 'c': 1 } } }
];
_.map(_.property('a.b.c'), objects);
// => [2, 1]
_.map('a.b.c', _.sortBy(objects, _.property(['a', 'b', 'c'])));
// => [1, 2]
The opposite of _.property
; this method creates a function that returns
the value at a given path of object
.
object
(Object): The object to query.
(Function): Returns the new function.
var array = [0, 1, 2],
object = { 'a': array, 'b': array, 'c': array };
_.map(_.propertyOf(object), ['a[2]', 'c[0]']);
// => [2, 0]
_.map(_.propertyOf(object), [['a', '2'], ['c', '0']]);
// => [2, 0]
Creates an array of numbers (positive and/or negative) progressing from
start
up to, but not including, end
. A step of -1
is used if a negative
start
is specified without an end
or step
. If end
is not specified
it's set to start
with start
then set to 0
.
Note: JavaScript follows the IEEE-754 standard for resolving
floating-point values which can produce unexpected results.
[start=0]
(number): The start of the range.end
(number): The end of the range.[step=1]
(number): The value to increment or decrement by.
(Array): Returns the new array of numbers.
_.range(4);
// => [0, 1, 2, 3]
_.range(-4);
// => [0, -1, -2, -3]
_.range(1, 5);
// => [1, 2, 3, 4]
_.range(0, 20, 5);
// => [0, 5, 10, 15]
_.range(0, -4, -1);
// => [0, -1, -2, -3]
_.range(1, 4, 0);
// => [1, 1, 1]
_.range(0);
// => []
This method is like _.range
except that it populates values in
descending order.
[start=0]
(number): The start of the range.end
(number): The end of the range.[step=1]
(number): The value to increment or decrement by.
(Array): Returns the new array of numbers.
_.rangeRight(4);
// => [3, 2, 1, 0]
_.rangeRight(-4);
// => [-3, -2, -1, 0]
_.rangeRight(1, 5);
// => [4, 3, 2, 1]
_.rangeRight(0, 20, 5);
// => [15, 10, 5, 0]
_.rangeRight(0, -4, -1);
// => [-3, -2, -1, 0]
_.rangeRight(1, 4, 0);
// => [1, 1, 1]
_.rangeRight(0);
// => []
Create a new pristine lodash
function using the context
object.
[context=root]
(Object): The context object.
(Function): Returns a new lodash
function.
_.mixin({ 'foo': _.constant('foo') });
var lodash = _.runInContext();
lodash.mixin({ 'bar': lodash.constant('bar') });
_.isFunction(_.foo);
// => true
_.isFunction(_.bar);
// => false
lodash.isFunction(lodash.foo);
// => false
lodash.isFunction(lodash.bar);
// => true
// Use `context` to mock `Date#getTime` use in `_.now`.
var mock = _.runInContext({
'Date': function() {
return { 'getTime': getTimeMock };
}
});
// Create a suped-up `defer` in Node.js.
var defer = _.runInContext({ 'setTimeout': setImmediate }).defer;
Invokes the iteratee function n
times, returning an array of the results
of each invocation. The iteratee is invoked with one argument; (index).
[iteratee=_.identity]
(Function): The function invoked per iteration.n
(number): The number of times to invokeiteratee
.
(Array): Returns the array of results.
_.times(String, 3);
// => ['0', '1', '2']
_.times(_.constant(true), 4);
// => [true, true, true, true]
Converts value
to a property path array.
value
(*): The value to convert.
(Array): Returns the new property path array.
_.toPath('a.b.c');
// => ['a', 'b', 'c']
_.toPath('a[0].b.c');
// => ['a', '0', 'b', 'c']
var path = ['a', 'b', 'c'],
newPath = _.toPath(path);
console.log(newPath);
// => ['a', 'b', 'c']
console.log(path === newPath);
// => false
Generates a unique ID. If prefix
is provided the ID is appended to it.
[prefix]
(string): The value to prefix the ID with.
(string): Returns the unique ID.
_.uniqueId('contact_');
// => 'contact_104'
_.uniqueId();
// => '105'
(string): The semantic version number.
(Object): By default, the template delimiters used by lodash are like those in embedded Ruby (ERB). Change the following template settings to use alternative delimiters.
(RegExp): Used to detect data
property values to be HTML-escaped.
(RegExp): Used to detect code to be evaluated.
(Object): Used to import variables into the compiled template.
(RegExp): Used to detect data
property values to inject.
(string): Used to reference the data object in the template text.
A reference to the lodash
function.