JavaScript Bitwise Operations

JavaScript bitwise operations work at the binary level, performing calculations directly on the binary representation of numbers. These operations are efficient and useful for low-level programming tasks like setting flags, masking, or optimizing performance.

Bitwise Operators

1. AND (&)

• Compares each bit of two numbers and returns 1 if both bits are 1, otherwise 0.

5 & 3; // 0101 & 0011 = 0001 (1 in decimal)

2. OR (|)

• Compares each bit of two numbers and returns 1 if at least one of the bits is 1.

5 | 3; // 0101 | 0011 = 0111 (7 in decimal)

3. XOR (^)

• Compares each bit of two numbers and returns 1 if the bits are different, otherwise 0.

5 ^ 3; // 0101 ^ 0011 = 0110 (6 in decimal)

4. NOT (~)

• Inverts all the bits of a number (1 becomes 0, and 0 becomes 1).

~5; // ~00000101 = 11111010 (-6 in decimal)

6. Right Shift (>>)

• Shifts the bits of the number to the right, preserving the sign bit (for signed numbers).

5 >> 1; // 0101 >> 1 = 0010 (2 in decimal)
-5 >> 1; // 11111011 >> 1 = 11111101 (-3 in decimal)

7. Unsigned Right Shift (>>>)

• Shifts the bits of the number to the right, filling with 0 from the left (ignoring the sign bit).

5 >>> 1; // 0101 >>> 1 = 0010 (2 in decimal)
-5 >>> 1; // 11111011 >>> 1 = 01111101 (2147483645 in decimal)

Practical Use Cases

1. Masking

• Isolate specific bits using the AND operator.

const mask = 0b0011; // Binary: 0011
const value = 0b1011; // Binary: 1011
const result = value & mask; // 0011 (Binary) = 3 (Decimal)

2. Setting a Bit

• Use OR to set a specific bit.

const value = 0b1010; // Binary: 1010
const bitToSet = 0b0100; // Binary: 0100
const result = value | bitToSet; // 1110 (Binary) = 14 (Decimal)

3. Clearing a Bit

• Use AND with the NOT operator to clear a specific bit.

const value = 0b1011; // Binary: 1011
const bitToClear = 0b0100; // Binary: 0100
const result = value & ~bitToClear; // 1011 & 1011 = 1011 (Binary) = 11 (Decimal)

4. Toggling a Bit

• Use XOR to toggle a specific bit.

const value = 0b1010; // Binary: 1010
const bitToToggle = 0b0100; // Binary: 0100
const result = value ^ bitToToggle; // 1110 (Binary) = 14 (Decimal)

5. Checking a Bit

• Use AND to check if a specific bit is set.

const value = 0b1011; // Binary: 1011
const bitToCheck = 0b0010; // Binary: 0010
const isSet = (value & bitToCheck) !== 0; // true