符号なし右シフト代入 (>>>=)

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.

符号なし右シフト代入演算子 (>>>=) は、指定された数だけビットを右に移動し、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; //  00000000000000000000000000000001
console.log(a);
// Expected output: 1

let b = -5; // -00000000000000000000000000000101

b >>>= 2; //  00111111111111111111111111111110
console.log(b);
// Expected output: 1073741822

構文

js
x >>>= y; // x = x >>> y

符号なし右シフト代入の使用

js
let a = 5; // (00000000000000000000000000000101)
a >>>= 2; // 1 (00000000000000000000000000000001)

let b = -5; // (-00000000000000000000000000000101)
b >>>= 2; // 1073741822 (00111111111111111111111111111110)

仕様書

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

ブラウザーの互換性

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Chrome
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Opera
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Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
Unsigned right shift assignment (x >>>= y)

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Full support
Full support

関連情報