Web/JavaScript/Reference/Operators/Left shift assignment

The left shift assignment operator (<<=) moves the specified amount of bits to the left and assigns the result to the variable.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

Operator: x <<= y
Meaning:  x   = x << y

Examples

Using left shift assignment

let a = 5; 
// 00000000000000000000000000000101

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

Specifications

Specification

ECMAScript (ECMA-262)The definition of 'Assignment operators' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
Left shift assignment (`x <<= y`)	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 3	Opera Full support 3	Safari Full support 1	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100

Legend

Full support: Full support