JavaScript Bitwise

Operator Table

Examples

JavaScript Uses 32 bits for Bitwise Operations

JavaScript stores numbers as 64-bit floating-point numbers but performs all bitwise operations on 32-bit binary numbers. Before performing a bitwise operation, JavaScript converts numbers to 32-bit signed integers. After the operation, the result is converted back to 64-bit numbers.

The examples above use 4-bit unsigned binary numbers. Due to this, ~6 returns -7.

‍

JavaScript Bitwise AND (&)

When a bitwise AND is performed on a pair of bits, it returns 1 if both bits are 1.

One-bit example:

‍

Four-bit example:

JavaScript Bitwise OR (|)

When a bitwise OR is performed on a pair of bits, it returns 1 if one of the bits is 1.

One-bit example:

‍

Four-bit example:

‍

JavaScript Bitwise XOR (^)

When a bitwise XOR is performed on a pair of bits, it returns 1 if the bits are different.

One-bit example:

‍

‍

‍

Four-bit example:

‍

‍

JavaScript Bitwise NOT (~)

Example:

‍

Example:

let x = ~6;

‍

JavaScript Zero Fill Left Shift (<<)

This is a zero fill left shift. One or more zero bits are pushed in from the right, and the leftmost bits fall off.

Example:

‍

Example:

let x = 6 << 2;

JavaScript Sign-Preserving Right Shift (>>)

This is a sign-preserving right shift. Copies of the leftmost bit are pushed in from the left, and the rightmost bits fall off.

Example:

‍

Example:

let x = 6 >>> 1;

Binary Numbers

Binary numbers with only one bit set are easy to understand:

‍

Setting a few more bits reveals the binary pattern:

JavaScript binary numbers are stored in two's complement format. This means that a negative number is the bitwise NOT of the number plus 1:

‍

‍

Converting Decimal to Binary

Example:

function dec2bin(dec) {
  return (dec >>> 0).toString(2);
}

Converting Binary to Decimal

Example:

function bin2dec(bin) {
  return parseInt(bin, 2).toString(10);
}