Left shift assignment (<<=)
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The left shift assignment (<<=
) operator performs left shift on the two operands and assigns the result to the left operand.
Try it
let a = 5; // 00000000000000000000000000000101
a <<= 2; // 00000000000000000000000000010100
console.log(a);
// Expected output: 20
Syntax
js
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
js
let a = 5;
// 00000000000000000000000000000101
a <<= 2; // 20
// 00000000000000000000000000010100
let b = 5n;
b <<= 2n; // 20n
Specifications
Specification |
---|
ECMAScript® 2025 Language Specification # sec-assignment-operators |
Browser compatibility
Report problems with this compatibility data on GitHubdesktop | mobile | server | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Left shift assignment ( x <<= y ) |
Legend
Tip: you can click/tap on a cell for more information.
- 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.