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

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

let bar = 5;
bar **= 2; // 25

Other non-BigInt values are coerced to numbers:

let baz = 5;
baz **= "foo"; // NaN

Exponentiation assignment using BigInts

let foo = 3n;
foo **= 2n; // 9n
foo **= 1; // TypeError: Cannot mix BigInt and other types, use explicit conversions

Specifications

Specification
ECMAScript® 2027 Language Specification # sec-assignment-operators

Browser compatibility

	Desktop					Mobile							Server
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on iOS	Samsung Internet	WebView Android	WebView on iOS	Bun	Deno	Node.js
`exponentiation_assignment`	52	14	52	39	10.1	52	52	41	10.3	6.0	51	10.3	1.0.0	1.0	7.0.0