左移赋值(<<=)

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.

左移赋值运算符(<<=)将变量向左移动指定的位数,并将结果赋值给变量。

尝试一下

let a = 5; // 00000000000000000000000000000101

a <<= 2; // 00000000000000000000000000010100

console.log(a);
// Expected output: 20

语法

js
x <<= y // x = x << y

示例

使用左移赋值

js
let a = 5;
// 00000000000000000000000000000101

a <<= 2; // 20
// 00000000000000000000000000010100

规范

Specification
ECMAScript® 2025 Language Specification
# sec-assignment-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
Left shift assignment (x <<= y)

Legend

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Full support
Full support

参考