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Left shift assignment (<<=)

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The left shift assignment (<<=) operator performs left shift on the two operands and assigns the result to the left operand.

{{InteractiveExample("JavaScript Demo: Left shift assignment (<<=) operator", "shorter")}}

```js interactive-example let a = 5; // 00000000000000000000000000000101

a <<= 2; // 00000000000000000000000000010100

console.log(a); // Expected output: 20

## Syntax

```js-nolint
x <<= y

Description#

x <<= y is equivalent to x = x << y, except that the expression x is only evaluated once.

Examples#

Using left shift assignment#

let a = 5;
// 00000000000000000000000000000101

a <<= 2; // 20
// 00000000000000000000000000010100

let b = 5n;
b <<= 2n; // 20n

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#