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

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()

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`	38	12	13	25	8	38	14	25	8	3.0	38	8	1.0.0	1.0	0.12.0