JS Arrays Cheatsheet

arrays.js

/** Static properties **/

// Creates an array from a String
// Output ['🍎', '🍌', '🍇']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/from
Array.from('🍎🍌🍇')

// Check for an array
// Output true
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray
Array.isArray(['🍎', '🍌', '🍇'])

// Creates a new Array with provided elements
// Output ['🍎', '🍌', '🍇']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/of
Array.of('🍎', '🍌', '🍇')

/** Instance properties */

// Joins two arrays
// Output ['🍎', '🍌', '🍇', '🍓']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/concat
['🍎', '🍌'].concat(['🍇', '🍓'])

// Copy first two array elements to last two
// Output: ['🍎', '🍌', '🍎', '🍌']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/copyWithin
['🍎', '🍌', '🍇', '🍓'].copyWithin(2, 0)

// Returns the array that matches the test
// Output ['🍎']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
['🍎', '🍌', '🍇'].filter(emoji => emoji === '🍎')

// Get the index of '🍌'
// Output 1
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf
['🍎', '🍌', '🍇'].indexOf('🍌')

// Returns the value of the first element that satisfies function 🍌
// Output: '🍌'
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/find
['🍎', '🍌', '🍇'].find(emoji => emoji === '🍌')


// Returns the index of the first element that satisfies function 🍌
// Output: 1
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex
['🍎', '🍌', '🍇'].findIndex(emoji => emoji === '🍌')

// Create a new array with all elements of nested arrays
// Ouput ['🍎', '🍌', '🍇', '🍓']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/flat
['🍎', '🍌', ['🍇', '🍓']].flat()

// Executes a provided function once for each array element
// Output 🍎🍌🍇
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach
['🍎', '🍌', '🍇'].forEach(emoji => console.log(emoji))

// Creates a new array by calling a function for each array element
// Output 🍎🍌🍇
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/map
['🍎', '🍌', '🍇'].map(emoji => console.log(emoji))

// Checks if every element in the array has a value 🍎
// Output false
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/every
['🍎', '🍌', '🍇'].every(emoji => emoji === '🍎')

// Checks if at least one element in the array has a value 🍎
// Output true
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/some
['🍎', '🍌', '🍇'].some(emoji => emoji === '🍎')

// Checks if the array contains '🍓'
// Output false
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/includes
['🍎', '🍌', '🍇'].includes('🍓')

// Joins all elements of an array into a string
// Output "🍎 - 🍌 - 🍇"
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/join
['🍎', '🍌', '🍇'].join(' - ')

// Removes and return the last element of an array
// Output '🍇'
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/pop
['🍎', '🍌', '🍇'].pop()

// Adds new elements to the end of an array and returns length
// Output 4
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/push
['🍎', '🍌', '🍇'].push('🍒')

// Reverses the order of the elements in the array
// Output ['🍇', '🍌', '🍎']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/reverse
['🍎', '🍌', '🍇'].reverse()

// Adds/Removes elements
// Output (removed array) ['🍌', '🍇'], (new array) ['🍎']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/splice
['🍎', '🍌', '🍇'].splice(1, 2)

// Selects a part of an array and returns the new array
// Output ['🍌']
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/slice
['🍎', '🍌', '🍇'].slice(1, 2)

// Converts an array to a string, and returns the result
// Output '🍎,🍌,🍇'
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/toString
['🍎', '🍌', '🍇'].toString()

// Remove the first element of an array, and return that element
// Output '🍎'
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/shift
['🍎', '🍌', '🍇'].shift()

// Add new elements to the beginning and returns the new length
// Output 4
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/unshift
['🍎', '🍌', '🍇'].unshift('🍐')

// Reduce the values of an array to a single value
// Output '🍌🍎🍌🍇'
// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce
['🍎', '🍌', '🍇'].reduce((acc, cur) => acc + cur, '🍌')