JS: Array.from

By Xah Lee. Date: . Last updated: .

New in ES2015.

[see JS: Iterable]

[see JS: “this” Binding]

Example: Convert Array-Like Object to Array

[see JS: Array-Like Object]

// create a array-like object
const alike = {0:"a", 1:"b" , length:2};

const ar = Array.from ( alike );

console.log ( ar ) // [ 'a', 'b' ]

console.log ( Array.isArray ( ar ) ); // true

Example: Iterable to Array

Convert set object to array.

const ss = new Set ([3,4,5]); // a set object

// convert set to array object
const ar = Array.from(ss);

console.log(ar) // [ 3, 4, 5 ]

Example: With Map Function

Array.from ( items, f ) example:

// a set object
const ss = new Set ([3,4,5]);

// convert to array, but add one to each
const ar = Array.from(ss, x => x +1);

console.log(ar); // [ 4, 5, 6 ]

Reference

ECMAScript® 2016 Language Specification#sec-array.from

JS Array

  1. Understand JS Array
  2. Create Array
  3. Sparse Array
  4. Array-Like Object
  5. Array How-To
  6. Array Object
  7. Array.prototype
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