べき乗代入 (**=)
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2017.
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べき乗代入演算子 (**=) は、変数の値を右オペランドでべき乗します。
試してみましょう
let a = 3;
console.log((a **= 2));
// Expected output: 9
console.log((a **= 0));
// Expected output: 1
console.log((a **= "hello"));
// Expected output: NaN
構文
js
x **= y; // x = x ** y
例
べき乗代入の仕様
js
// 次の変数を想定
// bar = 5
bar **= 2; // 25
bar **= "foo"; // NaN
仕様書
| Specification |
|---|
| ECMAScript® 2025 Language Specification # sec-assignment-operators |