べき乗代入 (**=)
BaselineWidely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2017.
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: 9console.log((a **= 0));// Expected output: 1console.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 = 5bar **= 2; // 25bar **= "foo"; // NaN仕様書
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-assignment-operators |