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 entry 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

has(key)

Parameters

key: The key of the entry to test for presence in the Map object. Object keys are compared by reference, not by value.

Return value

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

Examples

Using has()

const myMap = new Map();
myMap.set("bar", "foo");

console.log(myMap.has("bar")); // true
console.log(myMap.has("baz")); // false

Specifications

Specification
ECMAScript® 2027 Language Specification # sec-map.prototype.has

Browser compatibility

	Desktop					Mobile							Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS	Bun	Deno	Node.js
`has`	38	12	13	25	8	38	14	25	8	3.0	38	8	1.0.0	1.0	0.12.0