Set.prototype.has()

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 has() 方法返回一个布尔值来指示对应的值是否存在于该集合中。

尝试一下

语法

js
has(value)

参数

value

要测试是否存在于 Set 对象中的值。

返回值

如果 Set 对象中存在具有指定值的元素,则返回 true;否则返回 false

示例

使用 has() 方法

js
const mySet = new Set();
mySet.add("foo");

console.log(mySet.has("foo")); // true
console.log(mySet.has("bar")); // false

const set1 = new Set();
const obj1 = { key1: 1 };
set1.add(obj1);

console.log(set1.has(obj1)); // true
console.log(set1.has({ key1: 1 })); // false, 因为它们是不同的对象引用
console.log(set1.add({ key1: 1 })); // 现在 set1 包含 2 个条目

规范

Specification
ECMAScript Language Specification
# sec-set.prototype.has

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
has

Legend

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Full support
Full support

参见