JavaScript Bitwise Operations

JavaScript Bitwise Operators

Operator	Description	Example	Same as	Result	Same as
&	AND	5 & 1	0101 & 0001	1	0001
\|	OR	5 \| 1	0101 \| 0001	5	0101
~	NOT	~ 5	~0101	10	1010
^	XOR	5 ^ 1	0101 ^ 0001	4	0100
<<	Zero fill left shift	5 << 1	0101 << 1	10	1010
>>	Signed right shift	5 >> 1	0101 >> 1	2	0010
>>>	Zero fill right shift	5 >>> 1	0101 >>> 1	2	0010

The examples above uses 4 bits unsigned examples. But JavaScript uses 64 bits signed numbers.

Because of this (in JavaScript) ~ 5 will not return 10. It will return -6.

0000000000000000000000000000000000000000000000000000000000000101

will return:

1111111111111111111111111111111111111111111111111111111111111010

Bitwise AND

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

One bit example:

Operation	Result
0 & 0	0
0 & 1	0
1 & 0	0
1 & 1	1

4 bits example:

Operation	Result
1111 & 0000	0000
1111 & 0001	0001
1111 & 0010	0010
1111 & 0100	0100

Bitwise OR

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

One bit example:

Operation	Result
0 \| 0	0
0 \| 1	1
1 \| 0	1
1 \| 1	1

4 bits example:

Operation	Result
1111 \| 0000	1111
1111 \| 0001	1111
1111 \| 0010	1111
1111 \| 0100	1111

Bitwise XOR

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

One bit example:

Operation	Result
0 ^ 0	0
0 ^ 1	1
1 ^ 0	1
1 ^ 1	0

4 bits example:

Operation	Result
1111 ^ 0000	1111
1111 ^ 0001	1110
1111 ^ 0010	1101
1111 ^ 0100	1011

JavaScript Bitwise Operations

JavaScript bitwise operations works on 32 bits signed integers.

Any number in a bitwise operation is converted into a 32 bit signed integer.

The result of a bitwise operation is converted back into a JavaScript number.

JavaScript Bitwise AND (&)

Bitwise AND returns 1 only if both bits are 1:

Decimal	Binary
5	00000000000000000000000000000101
1	00000000000000000000000000000001
5 & 1	00000000000000000000000000000001 (1)

Example

var x = 5 & 1;

JavaScript Bitwise OR (|)

Bitwise or returns 1 if one of the bits are 1:

Decimal	Binary
5	00000000000000000000000000000101
1	00000000000000000000000000000001
5 \| 1	00000000000000000000000000000101 (5)

Example

var x = 5 | 1;

JavaScript Bitwise XOR (^)

Bitwise XOR returns 1 if the bits are different:

Decimal	Binary
5	00000000000000000000000000000101
1	00000000000000000000000000000001
5 ^ 1	00000000000000000000000000000100 (4)

Example

var x = 5 ^ 1;

JavaScript Bitwise NOT (~)

Decimal	Binary
5	00000000000000000000000000000101
~5	11111111111111111111111111111010 (-6)

Example

var x = ~5;

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:

Decimal	Binary
5	00000000000000000000000000000101
5 << 1	00000000000000000000000000001010 (10)

Example

var x = 5 << 1;

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:

Decimal	Binary
-5	11111111111111111111111111111011
-5 >> 1	11111111111111111111111111111101 (-3)

Example

var x = -5 >> 1;

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:

Decimal	Binary
5	00000000000000000000000000000101
5 >>> 1	00000000000000000000000000000010 (2)

Example

var x = 5 >>> 1;

Signed Numbers

Signed numbers with only one bit set is easy to understand:

Binary Representation	Decimal value
00000000000000000000000000000001	1
00000000000000000000000000000010	2
00000000000000000000000000000100	4
00000000000000000000000000001000	8
00000000000000000000000000010000	16
00000000000000000000000000100000	32
00000000000000000000000001000000	64

Setting a few more bits reveals the binary pattern:

Binary Representation	Decimal value
00000000000000000000000000000101	5 (4 + 1)
00000000000000000000000000001101	13 (8 + 4 + 1)
00000000000000000000000000101101	45 (32 + 8 + 4 + 1)

JavaScript numbers are stored in two's complement format.

This means that a negative number is the bitwise NOT of the number plus 1:

Binary Representation	Decimal value
00000000000000000000000000000101	5
11111111111111111111111111111011	-6
00000000000000000000000000101000	40
11111111111111111111111111011000	-41

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);
}

❮ Previous Next ❯

Operation	Result
0 \| 0	0
0 \| 1	1
1 \| 0	1
1 \| 1	1