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---
title: Exponentiation assignment (**=)
slug: Web/JavaScript/Reference/Operators/Exponentiation_assignment
page-type: javascript-operator
browser-compat: javascript.operators.exponentiation_assignment
sidebar: jssidebar
---
The **exponentiation assignment (`**=`)** operator performs [exponentiation](/en-US/docs/Web/JavaScript/Reference/Operators/Exponentiation) on the two operands and assigns the result to the left operand.
{{InteractiveExample("JavaScript Demo: Exponentiation assignment (**=) operator")}}
```js interactive-example
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-nolint
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
{{Specifications}}
## Browser compatibility
{{Compat}}
## See also
- [Assignment operators in the JS guide](/en-US/docs/Web/JavaScript/Guide/Expressions_and_operators#assignment_operators)
- [Exponentiation (`**`)](/en-US/docs/Web/JavaScript/Reference/Operators/Exponentiation)
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