Set.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 Set instances returns a boolean indicating whether an element with the specified value exists in this set or not.
Try it
const set1 = new Set([1, 2, 3, 4, 5]); console.log(set1.has(1)); // Expected output: true console.log(set1.has(5)); // Expected output: true console.log(set1.has(6)); // Expected output: false Syntax
js
has(value) Parameters
valueThe value to test for presence in the
Setobject.
Return value
Returns true if an element with the specified value exists in the Set object; otherwise false.
Examples
Using the has() method
js
const mySet = new Set(); mySet.add("foo"); console.log(mySet.has("foo")); // true console.log(mySet.has("bar")); // false const set1 = new Set(); const obj1 = { key1: 1 }; set1.add(obj1); console.log(set1.has(obj1)); // true console.log(set1.has({ key1: 1 })); // false, because they are different object references console.log(set1.add({ key1: 1 })); // now set1 contains 2 entries Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-set.prototype.has |
