严格不相等(!==)

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.

严格不相等运算符(!==)检查它的两个对象是否不相等,返回一个布尔结果。与不相等运算符不同,严格不相等运算符总是认为不同类型的对象是不同的。

尝试一下

console.log(1 !== 1);
// Expected output: false

console.log("hello" !== "hello");
// Expected output: false

console.log("1" !== 1);
// Expected output: true

console.log(0 !== false);
// Expected output: true

语法

js
x !== y

描述

严格不相等运算符检查其对象是否不相等。它是严格相等运算符的否定,因此下面两行总是会给出相同的结果:

js
x !== y;

!(x === y);

有关比较算法的详细信息,请参阅严格相等运算符的页面。

与严格相等运算符一样,严格不相等算符始终认为不同类型的对象是不同的:

js
3 !== "3"; // true

示例

比较相同类型的对象

js
"hello" !== "hello"; // false
"hello" !== "hola"; // true

3 !== 3; // false
3 !== 4; // true

true !== true; // false
true !== false; // true

null !== null; // false

比较不同类型的操作数

js
"3" !== 3; // true
true !== 1; // true
null !== undefined; // true

比较对象

js
const object1 = {
  key: "value",
};

const object2 = {
  key: "value",
};

console.log(object1 !== object2); // true
console.log(object1 !== object1); // false

规范

Specification
ECMAScript® 2025 Language Specification
# sec-equality-operators

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
Strict inequality (a !== b)

Legend

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Full support
Full support

参见