Set() constructor

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 Set() constructor creates Set objects.

Try it

const set = new Set([1, 2, 3, 4, 5]);

console.log(set.has(1));
// Expected output: true

console.log(set.has(5));
// Expected output: true

console.log(set.has(6));
// Expected output: false

Syntax

js
new Set()
new Set(iterable)

Note: Set() can only be constructed with new. Attempting to call it without new throws a TypeError.

Parameters

iterable Optional

If an iterable object (such as an array) is passed, all of its elements will be added to the new Set. If you don't specify this parameter, or its value is null or undefined, the new Set is empty.

Return value

A new Set object.

Examples

Using the Set object

js
const mySet = new Set();

mySet.add(1); // Set [ 1 ]
mySet.add(5); // Set [ 1, 5 ]
mySet.add(5); // Set [ 1, 5 ]
mySet.add("some text"); // Set [ 1, 5, 'some text' ]
const o = { a: 1, b: 2 };
mySet.add(o);