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