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
 Polyfill of Array.prototype.keys in core-js Array.prototype.values() Array.prototype.entries() Iteration protocols A polyfill 

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Last modified: Mar 8, 2022, by MDN contributors


    
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