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---
title: Map.prototype.keys()
short-title: keys()
slug: Web/JavaScript/Reference/Global_Objects/Map/keys
page-type: javascript-instance-method
browser-compat: javascript.builtins.Map.keys
sidebar: jsref
---
The **`keys()`** method of {{jsxref("Map")}} instances returns a new _[map iterator](/en-US/docs/Web/JavaScript/Reference/Global_Objects/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](/en-US/docs/Web/JavaScript/Reference/Global_Objects/Iterator).
## 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
{{Specifications}}
## Browser compatibility
{{Compat}}
## See also
- {{jsxref("Map.prototype.entries()")}}
- {{jsxref("Map.prototype.values()")}}
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