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map.has

The has() method returns a boolean indicating whether an element with the specified key exists or not.

Syntax

myMap.has(key)

Parameters

key
The key of the element to test for presence in the Map object.

Return value

true if an element with the specified key exists in the Map object; otherwise false.

Examples

Using has()

let myMap = new Map()
myMap.set('bar', "foo")

myMap.has('bar')   // returns true
myMap.has('baz')   // returns false

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
has 38 12 13 11 25 8
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
has 38 38 14 25 8 3.0
Server
Node.js
has 0.12
0.12
0.10
Disabled
Disabled From version 0.10: this feature is behind the --harmony runtime flag.

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/has