左移赋值（<<=） - JavaScript | MDN
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 2015年7月.
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
示例
使用左移赋值
js
let a = 5;
// 00000000000000000000000000000101
a <<= 2; // 20
// 00000000000000000000000000010100
规范
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-assignment-operators |