左シフト代入 (<<=)
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.
左シフト代入演算子 (<<=
) は、指定された数だけビットを左に移動し、結果を変数に代入します。
試してみましょう
let a = 5; // 00000000000000000000000000000101
a <<= 2; // 00000000000000000000000000010100
console.log(a);
// Expected output: 20
構文
js
x <<= y; // x = x << y
例
左シフト代入の使用
js
let a = 5;
// 00000000000000000000000000000101
a <<= 2; // 20
// 00000000000000000000000000010100
仕様書
Specification |
---|
ECMAScript® 2025 Language Specification # sec-assignment-operators |
ブラウザーの互換性
Report problems with this compatibility data on GitHubdesktop | mobile | server | ||||||||||||
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Left shift assignment ( x <<= y ) |
Legend
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- Full support
- Full support
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.