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Array.prototype.keys()

The keys() method returns a new Array Iterator object that contains the keys for each index in the array.

Try it

Syntax

keys()

Return value

A new Array iterator object.

Examples

Key iterator doesn't ignore holes

const arr = ['a', , 'c'];
const sparseKeys = Object.keys(arr);
const denseKeys = [...arr.keys()];
console.log(sparseKeys); // ['0', '2']
console.log(denseKeys);  // [0, 1, 2]

Specifications

Specification
ECMAScript Language Specification
# sec-array.prototype.keys

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet Deno Node.js
keys
38
12
28
No
25
8
38
38
28
25
8
3.0
1.0
0.12.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/keys