Set.prototype.add()
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 add() method of Set instances inserts the specified value into this set, if it is not already present.
Try it
const set = new Set();
set.add(42);
set.add(42);
set.add(13);
for (const item of set) {
console.log(item);
// Expected output: 42
// Expected output: 13
}
Syntax
js
add(value)
Parameters
Return value
The Set object.
Examples
Using add()
js
const mySet = new Set();
mySet.add(1);
mySet.add(5).add("some text"); // chainable
console.log(mySet);
// Set [1, 5, "some text"]
Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-set.prototype.add |