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

value

The value to add to the Set object. Objects are compared by reference, not by value.

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® 2027 Language Specification
# sec-set.prototype.add

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
add
Chrome – Full support
Chrome 38 (Release date: 2014-10-07)
footnote Full support
Edge – Full support
Edge 12 (Release date: 2015-07-29)
footnote Full support
Firefox – Full support
Firefox 13 (Release date: 2012-06-05)
footnote Full support
Opera – Full support
Opera 25 (Release date: 2014-10-15)
footnote Full support
Safari – Full support
Safari 8 (Release date: 2014-10-16)
footnote Full support
Chrome Android – Full support
Chrome Android 38 (Release date: 2014-10-08)
footnote Full support
Firefox for Android – Full support
Firefox for Android 14 (Release date: 2012-06-26)
footnote Full support
Opera Android – Full support
Opera Android 25 (Release date: 2014-10-16)
footnote Full support
Safari on iOS – Full support
Safari on iOS 8 (Release date: 2014-09-17)
footnote Full support
Samsung Internet – Full support
Samsung Internet 3 (Release date: 2015-04-10)
footnote Full support
WebView Android – Full support
WebView Android 38 (Release date: 2014-10-08)
footnote Full support
WebView on iOS – Full support
WebView on iOS 8 (Release date: 2014-09-17)
footnote Full support
Bun – Full support
Bun 1 (Release date: 2023-09-08)
footnote Full support
Deno – Full support
Deno 1 (Release date: 2020-05-13)
footnote Full support
Node.js – Full support
Node.js 0.12 (Release date: 2015-02-06)
footnote Full support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support

See also