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: Expressions - Left shift assignment operator", "shorter")}}

let a = 5; // 00000000000000000000000000000101

a <<= 2; // 00000000000000000000000000010100

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

Syntax

x <<= y

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

let a = 5;
// 00000000000000000000000000000101

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

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

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