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.

Set 实例的 size 访问器属性将返回该集合中(唯一的)元素的个数。

尝试一下

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

描述

size 的值是一个整数,表示 Set 对象有多少条目。size 的 set 访问函数是 undefined;你无法改变这个属性。

示例

使用 size

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

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

规范

Specification
ECMAScript® 2025 Language Specification
# sec-get-set.prototype.size

浏览器兼容性

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
size

Legend

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

Full support
Full support
See implementation notes.

参见