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 **= yx = 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® 2025 Language Specification
# sec-assignment-operators

浏览器兼容性

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
Exponentiation assignment (x **= y)

Legend

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Full support
Full support

参见