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

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

const mySet = new Set();
mySet.add(1);
mySet.add(5);
mySet.add("some text");

console.log(mySet.size); // 3

Specifications

Specification
ECMAScript Language Specification
# sec-get-set.prototype.size

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android Deno Node.js
size 38 12
19From Firefox 13 to Firefox 18, the size property was implemented as a Set.prototype.size() method, this has been changed to a property in later versions conform to the ECMAScript 2015 specification.
 25 8 38
19From Firefox for Android 14 to Firefox for Android 18, the size property was implemented as a Set.prototype.size() method, this has been changed to a property in later versions conform to the ECMAScript 2015 specification.
 25 8 3.0 38 1.0 0.12.0

See also

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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/size