The has()
method returns a boolean indicating whether an element with the specified key exists or not.
myMap.has(key);
Map
object.true
if an element with the specified key exists in the Map
object; otherwise false
.has
methodvar myMap = new Map(); myMap.set('bar', "foo"); myMap.has('bar'); // returns true myMap.has('baz'); // returns false
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Map.prototype.has' in that specification. | Standard | Initial definition. |
ECMAScript Latest Draft (ECMA-262) The definition of 'Map.prototype.has' in that specification. | Draft |
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 38 | 12 | 13 | 11 | 25 | 8 |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | Opera Android | iOS Safari | Samsung Internet |
---|---|---|---|---|---|---|---|
Basic support | 38 | 38 | 12 | 14 | 25 | 8 | ? |
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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/has