JavaScript Bitwise Operations

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JavaScript Bitwise Operations


JavaScript Bitwise Operators


Operator
Name
Description


&
AND
Sets each bit to 1 if both bits are 1


|
OR
Sets each bit to 1 if one of two bits is 1


^
XOR
Sets each bit to 1 if only one of two bits is 1


~
NOT
Inverts all the bits


<<
Zero fill left shift
Shifts left by pushing zeros in from the right and let the leftmost bits fall off


>>
Signed right shift
Shifts right by pushing copies of the leftmost bit in from the left, and let the rightmost bits
fall off


>>>
Zero fill right shift
Shifts right by pushing zeros in from the left, and let the rightmost bits fall off


Examples



Operation
Result
Same as
Result


5 & 1
1
0101 & 0001
 0001


5 | 1
5
0101 | 0001
 0101


~ 5
10
 ~0101
 1010


5 << 1
10
0101 << 1
 1010


5 ^ 1
4
0101 ^ 0001
 0100


5 >> 1
2
0101 >> 1
 0010


5 >>> 1
2
0101 >>> 1
 0010




JavaScript Uses 32 bits Bitwise Operands
JavaScript stores numbers as 64 bits floating point numbers, but all bitwise
operations are performed on 32 bits binary numbers.
Before a bitwise operation is performed, JavaScript converts numbers to 32 bits
signed integers.
After the bitwise operation is performed, the result is converted back to 64 bits JavaScript
numbers.

The examples above uses 4 bits unsigned binary numbers. Because of this ~ 5 returns 10.
Since JavaScript uses 32 bits signed integers, it will not return 10. It will return -6.
00000000000000000000000000000101 (5)
11111111111111111111111111111010 (~5 = -6)
A signed integer uses the leftmost bit as the minus sign.










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:

OperationResult
0 & 00
0 & 10
1 & 00
1 & 11



4 bits example:

OperationResult
1111 & 00000000
1111 & 00010001
1111 & 00100010
1111 & 01000100




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:

OperationResult
0 | 00
0 | 11 
1 | 01
1 | 11



4 bits example:

OperationResult
1111 | 00001111
1111 | 00011111
1111 | 00101111
1111 | 01001111




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:

OperationResult
0 ^ 00
0 ^ 11 
1 ^ 01
1 ^ 10 



4 bits example:

OperationResult
1111 ^ 00001111
1111 ^ 00011110
1111 ^ 00101101
1111 ^ 01001011




JavaScript Bitwise AND (&)
Bitwise AND returns 1 only if both bits are 1:

DecimalBinary
500000000000000000000000000000101
100000000000000000000000000000001
5 & 100000000000000000000000000000001 (1)


Example

let x = 5 & 1;

Try it Yourself »


JavaScript Bitwise OR (|)
Bitwise OR returns 1 if one of the bits is 1:

DecimalBinary
500000000000000000000000000000101
100000000000000000000000000000001
5 | 100000000000000000000000000000101 (5)


Example

let x = 5 | 1;

Try it Yourself »


JavaScript Bitwise XOR (^)
Bitwise XOR returns 1 if the bits are different:

DecimalBinary
500000000000000000000000000000101
100000000000000000000000000000001
5 ^ 100000000000000000000000000000100 (4)


Example

let x = 5 ^ 1;

Try it Yourself »


JavaScript Bitwise NOT (~)

DecimalBinary
500000000000000000000000000000101
~511111111111111111111111111111010 (-6)


Example

let x = ~5;

Try it Yourself »


JavaScript (Zero Fill) Bitwise 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:

DecimalBinary
500000000000000000000000000000101
5 << 100000000000000000000000000001010 (10)


Example

let x = 5 << 1;

Try it Yourself »


JavaScript (Sign Preserving) Bitwise 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:

DecimalBinary
-511111111111111111111111111111011
-5 >> 111111111111111111111111111111101 (-3)


Example

let x = -5 >> 1;

Try it Yourself »


JavaScript (Zero Fill) Right Shift (>>>)
This is a zero fill right shift. One or more zero bits are pushed in from the left,
and the rightmost bits fall off:

DecimalBinary
500000000000000000000000000000101
5 >>> 100000000000000000000000000000010 (2)


Example

let x = 5 >>> 1;

Try it Yourself »


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

Binary RepresentationDecimal value
000000000000000000000000000000011
000000000000000000000000000000102
000000000000000000000000000001004
000000000000000000000000000010008
0000000000000000000000000001000016
0000000000000000000000000010000032
0000000000000000000000000100000064

Setting a few more bits reveals the binary pattern:

Binary RepresentationDecimal value
000000000000000000000000000001015 (4 + 1)
0000000000000000000000000000110113 (8 + 4 + 1)
0000000000000000000000000010110145 (32 + 8 + 4 + 1)

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:

Binary RepresentationDecimal value
000000000000000000000000000001015
11111111111111111111111111111011-5
000000000000000000000000000001106
11111111111111111111111111111010-6
0000000000000000000000000010100040
11111111111111111111111111011000-40


Joke:
There are only 10 types of people in the world: those who understand binary and those who don't.

Converting Decimal to Binary

Example

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

Try it Yourself »


Converting Binary to Decimal

Example

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

Try it Yourself »













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Reference: https://www.w3schools.com/js/js_bitwise.asp