Map.prototype.keys()

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.

The keys() method of Map instances returns a new map iterator object that contains the keys for each element in this map in insertion order.

Try it

Syntax

js
keys()

Parameters

None.

Return value

A new iterable iterator object.

Examples

Using keys()

js
const myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");

const mapIter = myMap.keys();

console.log(mapIter.next().value); // "0"
console.log(mapIter.next().value); // 1
console.log(mapIter.next().value); // {}

Specifications

Specification
ECMAScript Language Specification
# sec-map.prototype.keys

Browser compatibility

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See also