Array.prototype.keys()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. Itâs been available across browsers since 2015å¹´7æ.
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const array1 = ["a", "b", "c"];
const iterator = array1.keys();
for (const key of iterator) {
console.log(key);
}
// Expected output: 0
// Expected output: 1
// Expected output: 2
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arr.keys()
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js
var arr = ["a", , "c"];
var sparseKeys = Object.keys(arr);
var denseKeys = [...arr.keys()];
console.log(sparseKeys); // ['0', '2']
console.log(denseKeys); // [0, 1, 2]
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| Specification |
|---|
| ECMAScript® 2027 Language Specification # sec-array.prototype.keys |