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ビット論理積代入演算子 (&=) - JavaScript | MDN
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ビット論理積代入演算子 (&=)
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.
ビット論理積代入 (&=) 演算子は、 2 つのオペランドで論理積を取り、その結果を左オペランドへ代入します。
試してみましょう
let a = 5; // 00000000000000000000000000000101
a &= 3; // 00000000000000000000000000000011
console.log(a); // 00000000000000000000000000000001
// 予想される結果: 1
構文
js
x &= y
解説
x &= y は x = x & y と同等ですが、 x は一度しか評価されません。
例
ビット論理積代入の使用
js
let a = 5;
// 5: 00000000000000000000000000000101
// 2: 00000000000000000000000000000010
a &= 2; // 0
let b = 5n;
b &= 2n; // 0n
仕様書
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-assignment-operators |
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