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

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