幂赋值（**=）
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.
幂赋值（**=）对两个操作数执行幂运算，并将结果赋给左操作数。
尝试一下
let a = 3;
console.log((a **= 2));
// Expected output: 9
console.log((a **= 0));
// Expected output: 1
console.log((a **= 'hello'));
// Expected output: NaN
语法
js
x **= y
描述
x **= y 和 x = x ** y 是等价的，不同之处在于前者的 x 只被计算一次。
示例
使用数字进行幂赋值
js
let bar = 5;
bar **= 2; // 25
其他非 BigInt 值会被强制转换为数字：
js
let baz = 5;
baz **= "foo"; // NaN
使用 BigInt 进行幂赋值
js
let foo = 3n;
foo **= 2n; // 9n
foo **= 1; // TypeError: Cannot mix BigInt and other types, use explicit conversions
规范
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-assignment-operators |