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
Syntax
js
has(value)
Parameters
value-
The 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 Language Specification # sec-set.prototype.has |
Browser compatibility
| desktop | mobile | server | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
has | |||||||||||||