Map.prototype.keys()

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

{{InteractiveExample("JavaScript Demo: Map.prototype.keys()")}}

```js interactive-example const map = new Map();

map.set("0", "foo"); map.set(1, "bar");

const iterator = map.keys();

console.log(iterator.next().value); // Expected output: "0"

console.log(iterator.next().value); // Expected output: 1

## Syntax

```js-nolint
keys()

Parameters#

None.

Return value#

A new iterable iterator object.

Examples#

Using keys()#

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#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Map.prototype.entries()")}}
• {{jsxref("Map.prototype.values()")}}