Set.prototype.size
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 size
accessor property of Set
instances returns the number of (unique) elements in this set.
Try it
const set1 = new Set();
const object1 = {};
set1.add(42);
set1.add("forty two");
set1.add("forty two");
set1.add(object1);
console.log(set1.size);
// Expected output: 3
Description
The value of size
is an integer representing how many entries the Set
object has. A set accessor function for size
is undefined
; you cannot change this property.
Examples
Using size
js
const mySet = new Set();
mySet.add(1);
mySet.add(5);
mySet.add("some text");
console.log(mySet.size); // 3
Specifications
Specification |
---|
ECMAScript® 2025 Language Specification # sec-get-set.prototype.size |
Browser compatibility
Report problems with this compatibility data on GitHubdesktop | mobile | server | ||||||||||||
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size |
Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- See implementation notes.
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.