Map.prototype.has()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The has() method of Map instances returns a boolean indicating whether an element with the
specified key exists in this map or not.
Try it
const map = new Map();
map.set("bar", "foo");
console.log(map.has("bar"));
// Expected output: true
console.log(map.has("baz"));
// Expected output: false
Syntax
js
has(key)
Parameters
key-
The key of the element to test for presence in the
Mapobject.
Return value
true if an element with the specified key exists in the Map object;
otherwise false.
Examples
Using has()
js
const myMap = new Map();
myMap.set("bar", "foo");
console.log(myMap.has("bar")); // true
console.log(myMap.has("baz")); // false
Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-map.prototype.has |
Browser compatibility
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