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A set of pure ES2015 functions aimed to make functional JavaScript more idiomatic.
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// array utils | |
// ================================================================================================= | |
const combine = (...arrays) => [].concat(...arrays); | |
const compact = arr => arr.filter(Boolean); | |
const contains = (() => Array.prototype.includes | |
? (arr, value) => arr.includes(value) | |
: (arr, value) => arr.some(el => el === value) | |
)(); | |
const difference = (arr, ...others) => { | |
var combined = [].concat(...others) | |
return arr.filter(el => !combined.some(exclude => el === exclude)) | |
}; | |
const head = arr => arr[0]; | |
const initial = arr => arr.slice(0, -1); | |
const intersection = (...arrays) => | |
[...Set([].concat(...arrays))].filter(toFind => | |
arrays.every(arr => arr.some(el => el === toFind)) | |
); | |
const last = arr => arr.slice(-1)[0]; | |
const sortedIndex = (arr, value) => | |
[value].concat(arr).sort().indexOf(value); | |
const tail = arr => arr.slice(1); | |
const toArray = (() => Array.from ? Array.from : obj => [].slice.call(obj))(); | |
const union = (...arrays) => [...Set([].concat(...arrays))]; | |
const unique = arr => [...Set(arr)]; | |
const without = (arr, ...values) => | |
arr.filter(el => !values.some(exclude => el === exclude)); | |
// object utils | |
// ================================================================================================= | |
const getValues = obj => Object.keys(obj).map(key => obj[key]); | |
const merge = (() => { | |
const extend = Object.assign ? Object.assign : (target, ...sources) => { | |
sources.forEach(source => | |
Object.keys(source).forEach(prop => target[prop] = source[prop]) | |
); | |
return target; | |
}; | |
return (...objects) => extend({}, ...objects); | |
})(); | |
const toMap = (() => { | |
const convert = obj => new Map(Object.keys(obj).map(key => [key, obj[key]])); | |
return obj => obj instanceof Map ? obj : convert(obj); | |
})(); | |
// math | |
// ================================================================================================= | |
const min = arr => Math.min(...arr); | |
const max = arr => Math.max(...arr); | |
const sum = arr => arr.reduce((a, b) => a + b); | |
const product = arr => arr.reduce((a, b) => a * b); | |
// function decorators | |
// ================================================================================================= | |
const not = fn => (...args) => !fn(...args); | |
const maybe = fn => | |
(...args) => { | |
if (args.length < fn.length || args.some(arg => arg == null)) return; | |
return fn(...args); | |
}; | |
const once = fn => { | |
var done = false; | |
return (...args) => { | |
if (done) return; | |
done = true; | |
fn(...args); | |
}; | |
}; | |
const curry = fn => { | |
const arity = fn.length; | |
const curried = (...args) => | |
args.length < arity ? (...more) => curried(...args, ...more) : fn(...args); | |
return curried; | |
}; | |
const pipeline = (...funcs) => | |
value => funcs.reduce((a, b) => b(a), value); |
Most of these have horrible asymptotic performance.
compact
could be shortened to:
const identity = x => x
const compact = arr => arr.filter(identity)
Or even
const compact = arr => arr.filter(Boolean)
@joeybaker: Cleaner indeed, updated! Thanks :)
you sir ! are a legend.
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FYI: assign should eventually be shimmed via
Object.getOwnPropertySymbols
which might be there, but not necessarily in browsers that support assign too.https://github.com/WebReflection/get-own-property-symbols