JavaScript - right shift assignment operator
The Bitwise right shift assignment operator (>>=) assigns the first operand a value equal to the result of Bitwise right shift operation of two operands.
(x >>= y) is equivalent to (x = x >> y)
The Bitwise right shift operator (>>) takes the two numbers and right shift the bits of first operand by number of place specified by second operand. For example: for right shifting the bits of x by y places, the expression (x>>y) can be used. It is equivalent to dividing x by 2y.
The example below describes how right shift operator works:
1000 >> 2 returns 250 (In Binary) 1000 -> 1111101000 >> 2 | right shift the bits ----- V by 2 places 250 <- 11111010 (In Binary)
The code of using right shift operator (>>) is given below:
var x = 1000; var txt; //right shift assignment operation x >>= 2; txt = "x = " + x;
The output (value of txt) after running above script will be:
x = 250
Example: Find largest power of 2 less than or equal to given number
Consider an integer 1000. In the bit-wise format, it can be written as 1111101000. However, all bits are not written here. A complete representation will be 32 bit representation as given below:
00000000000000000000001111101000
Performing
00000000000000000000001111111111
Adding one to this result and then right shifting the result by one place will give largest power of 2 less than or equal to 1000.
00000000000000000000001000000000
The below code will calculate the largest power of 2 less than or equal to given number.
function MaxPowerOfTwo(N) { //changing all right side bits to 1. N = N | (N>>1); N = N | (N>>2); N = N | (N>>4); N = N | (N>>8); N = N | (N>>16); //adding 1 to N makes smallest power //of 2 greater than given number N = N + 1; //right shift by one position makes //largest power of 2 less than or //equal to given number N >>= 1; return N; } var txt; txt = "MaxPowerOfTwo(100) = " + MaxPowerOfTwo(100) + "<br>"; txt = txt + "MaxPowerOfTwo(500) = " + MaxPowerOfTwo(500) + "<br>"; txt = txt + "MaxPowerOfTwo(1000) = " + MaxPowerOfTwo(1000)+ "<br>";
The output (value of txt) after running above script will be:
MaxPowerOfTwo(100) = 64 MaxPowerOfTwo(500) = 256 MaxPowerOfTwo(1000) = 512
❮ JavaScript - Operators