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Map.prototype.keys()

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

Desktop Mobile Server
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android Deno Node.js
keys 38 12 20 25 8 38 20 25 8 3.0 38 1.0 0.12.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/keys