Array.prototype.entries()
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Theentries() method ofArray instances returns a newarray iterator object that contains the key/value pairs for each index in the array.
Try it
const array = ["a", "b", "c"];const iterator = array.entries();console.log(iterator.next().value);// Expected output: Array [0, "a"]console.log(iterator.next().value);// Expected output: Array [1, "b"]Syntax
js
entries()Parameters
None.
Return value
A newiterable iterator object.
Description
When used onsparse arrays, theentries() method iterates empty slots as if they have the valueundefined.
Theentries() method isgeneric. It only expects thethis value to have alength property and integer-keyed properties.
Examples
Iterating with index and element
js
const a = ["a", "b", "c"];for (const [index, element] of a.entries()) { console.log(index, element);}// 0 'a'// 1 'b'// 2 'c'Using a for...of loop
js
const array = ["a", "b", "c"];const arrayEntries = array.entries();for (const element of arrayEntries) { console.log(element);}// [0, 'a']// [1, 'b']// [2, 'c']Iterating sparse arrays
entries() will visit empty slots as if they areundefined.
js
for (const element of [, "a"].entries()) { console.log(element);}// [0, undefined]// [1, 'a']Calling entries() on non-array objects
Theentries() method reads thelength property ofthis and then accesses each property whose key is a nonnegative integer less thanlength.
js
const arrayLike = { length: 3, 0: "a", 1: "b", 2: "c", 3: "d", // ignored by entries() since length is 3};for (const entry of Array.prototype.entries.call(arrayLike)) { console.log(entry);}// [ 0, 'a' ]// [ 1, 'b' ]// [ 2, 'c' ]Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-array.prototype.entries |