JavaScript Map has()
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Definition and usage
has() The method is used to check if a key exists in the Map, and returns true if it does.
Instance
Example 1
// Create a Map
const fruits = new Map([
["apples", 500],
["bananas", 300],
["oranges", 200]
]);
// Is there "apples" in the Map?
fruits.has("apples");
Example 2
Try the following operations:
fruits.delete("apples");
fruits.has("apples");
Syntax
map.has(value)Parameter
| Parameter | Description |
|---|---|
| value | Required. The key to check. |
Return value
| Type | Description |
|---|---|
| Boolean | Returns true if the key exists, otherwise returns false. |
Browser support
map.has() Is a feature of ECMAScript6 (ES6).
Starting from June 2017, all modern browsers support ES6 (JavaScript 2015):
| Chrome | Edge | Firefox | Safari | Opera |
|---|---|---|---|---|
| Chrome 51 | Edge 15 | Firefox 54 | Safari 10 | Opera 38 |
| 2016 May | 2017 April | 2017 June | September 2016 | June 2016 |
map.has() Not supported in Internet Explorer.
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