Exponentiation assignment (**=)
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.
The exponentiation assignment (**=
) operator performs exponentiation on the two operands and assigns the result to the left operand.
Try it
let a = 3;
console.log((a **= 2));
// Expected output: 9
console.log((a **= 0));
// Expected output: 1
console.log((a **= 'hello'));
// Expected output: NaN
Syntax
js
x **= y
Description
x **= y
is equivalent to x = x ** y
, except that the expression x
is only evaluated once.
Examples
Exponentiation assignment using numbers
js
let bar = 5;
bar **= 2; // 25
Other non-BigInt values are coerced to numbers:
js
let baz = 5;
baz **= "foo"; // NaN
Exponentiation assignment using BigInts
js
let foo = 3n;
foo **= 2n; // 9n
foo **= 1; // TypeError: Cannot mix BigInt and other types, use explicit conversions
Specifications
Specification |
---|
ECMAScript® 2025 Language Specification # sec-assignment-operators |
Browser compatibility
Report problems with this compatibility data on GitHubdesktop | mobile | server | ||||||||||||
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Exponentiation assignment ( x **= y ) |
Legend
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- Full support
- Full support
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.