JavaScript (ES2026) reference · Array Methods

JavaScript Array keys() Method

Return an iterator of the array's indexes, including indexes of empty slots.

JavaScript (ES2026) Since ES2015

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Syntax

array.keys()

An array iterator.

All indexesTry it yourself

console.log([..."abc".split("").keys()]);

Output

[ 0, 1, 2 ]

keys() includes holes; Object.keys() doesn'tTry it yourself

const sparse = ["a", , "c"];
console.log([...sparse.keys()], Object.keys(sparse));

Output

[ 0, 1, 2 ] [ '0', '2' ]

Version	Change
JavaScript ES2015	Added

array.entries() · Return an iterator of [index, element] pairs, handy for looping with both the index and the value.
array.values() · Return an iterator of the array's values, the same thing a for…of loop uses.
JavaScript Arrays · tutorial
JavaScript Array Methods · tutorial