JavaScript - Bitwise AND assignment operator
The Bitwise AND assignment operator (&=) assigns the first operand a value equal to the result of Bitwise AND operation of two operands.
(x &= y) is equivalent to (x = x & y)
The Bitwise AND operator (&) is a binary operator which takes two bit patterns of equal length and performs the logical AND operation on each pair of corresponding bits. It returns 1 if both bits at the same position are 1, else returns 0.
Bit_1 | Bit_2 | Bit_1 & Bit_2 |
---|---|---|
0 | 0 | 0 |
1 | 0 | 0 |
0 | 1 | 0 |
1 | 1 | 1 |
The example below describes how bitwise AND operator works:
50 & 25 returns 16 50 -> 110010 (In Binary) & 25 -> & 011001 (In Binary) ---- -------- 16 <- 010000 (In Binary)
The code of using Bitwise AND assignment operator (&=) is given below:
var x = 50; var y = 25; var txt; //Bitwise AND assignment operation x &= y; txt = "x = " + x;
The output (value of txt) after running above script will be:
x = 16
Example: Check if a number is even or odd
The last bit of an even number is always 0, whereas for an odd number the last bit is always 1. Therefore, for a given number n, (n & 1) returns 0 if the n is even, else returns 1.
Even Number: 50 -> 110010 (In Binary) & 1 -> & 000001 (In Binary) ---- -------- 0 <- 000000 Odd Number: 99 -> 1100011 (In Binary) & 1 -> & 0000001 (In Binary) ---- --------- 1 <- 0000001
The below code checks whether a given number is even or odd:
function CheckEven(MyNum) { var x = MyNum; x &= 1; if (x == 1) return MyNum + " is an odd number.<br>"; else return MyNum + " is an even number.<br>"; } var txt; txt = CheckEven(50); txt = txt + CheckEven(99);
The output (value of txt) after running above script will be:
50 is an even number. 99 is an odd number.
❮ JavaScript - Operators