JavaScript Array.from() Method

The Array.from() method is used to create a new array from an array-like or iterable object. It provides an easy way to convert objects like strings, sets, maps, or node lists into a proper array.

Syntax

Array.from(arrayLike, mapFunction, thisArg);

Parameters

Parameter	Description
arrayLike	(Required) The array-like or iterable object to be converted into an array.
mapFunction	(Optional) A function to call on every element of the array, similar to Array.prototype.map().
thisArg	(Optional) A value to use as this when executing the mapFunction. If not provided, it defaults to undefined.

Return Value

The Array.from() method returns a new array populated with elements from the provided arrayLike object. If a mapFunction is provided, the resulting array elements are the result of calling the mapFunction on each element.

Example 1: Converting a String to an Array

let str = "hello";
let arr = Array.from(str);
console.log(arr); // Output: ['h', 'e', 'l', 'l', 'o']

Example 2: Using mapFunction for Transformation

let numbers = Array.from([1, 2, 3], num => num * 2);
console.log(numbers); // Output: [2, 4, 6]

Here, the mapFunction multiplies each element of the input array by 2 while creating the new array.

Example 3: Converting a Set to an Array

let mySet = new Set([10, 20, 30]);
let arr = Array.from(mySet);
console.log(arr); // Output: [10, 20, 30]

Example 5: Creating Arrays with Custom Lengths

let arr = Array.from({ length: 5 }, (_, i) => i + 1);
console.log(arr); // Output: [1, 2, 3, 4, 5]

Here, Array.from() is used to create an array of length 5, where each element is the index plus 1.

Supported Browsers

Browser	Support
Chrome	45+
Firefox	32+
Safari	9+
Edge	12+
Opera	32+
Internet Explorer	Not supported (requires polyfill)

Note:

The Array.from() method was introduced in ECMAScript 6 (ES6) and is widely supported in modern browsers. For compatibility with older browsers like Internet Explorer, a polyfill is necessary.