“Woman with hair over face lying down on cracked desert floor because bitwise operations are depressing” by Oscar Keys on Unsplash

Bitfoolish Operations in Javascript.

We all probably have never really had the need to do a single bitwise operation as developers, but some of the most important operations/functionalities used in programming use bitwise operations with the most popular (I think) being encryption.

Bitwise operations are, for the lack of a better word, intentional operations, carried out directly on the smallest representation of data that a computer can process…bits, using specific operators.

Bit, Byte, Bitten.

So while we deal with decimals (base 10s) on a day to day processing and interpretation of data, bitwise ops’ deal with binaries…0s and 1s and are of 7 types:

P.S. We will be using the bit representations of 4 and 5 in our examples which are 0100 and 0101 respectively.

1. AND

Each bit is compared to the bits of the other using the & operator and 1 returned where both bits compared are 1.

0100 = 4 in base 10. So, 4 & 5 = 4.

2. OR

Each bit is compared using the | operator and 1 is returned where either of the bits compared have 1.

0101 = 5 in base 10. So, 4 | 5 = 5

3. XOR

Each bit is compared using the ^ operator and 1 is returned when either of the compared bits are 1 and not both.

0001 = 1 in base 10. So 4 ^ 5 = 1.

4. NOT

Inverts bits using the ~ operator.

~4 = ~0100 = 1011 = -5 (your eyes do not deceive you. All NOT operations yield -(a + 1) as their value)

5. LEFT SHIFT (shl)

Each bit is shifted to left by the designated amount and the tail appended with a 0 for each step using the << operator and the head is truncated.

4 << 1 === 0100 << 1 = 1000 = 8
5 << 2 === 0101 << 2 = 0001 0100 = 20

6. RIGHT SHIFT (shr)

Each bit is shifted right by the designated amount and the head appended with the same bit signature that was there before, using the >> operator. So if it was a 1 there, 1s keep getting added and versa.

4 >> 1 === 0100 >> 1 = 0010 = 2

7. ZERO FILL RIGHT SHIFT

Each bit is shifted right by the designated amount and the head appended with 0 irrespective of what the leftmost bit was using the >>> operator.

4 >>> 1 === 0100 >>> 1 = 0010 = 2.

Can this punishment please end?

Armed with some of these, we can do some pretty nice arithmetic with bitwise operations instead of our usual decimal maths.

Have a Javascript event and you’re looking for speakers, or you’re working on something awesome and need some tech assistance? Please…do reach out to me on twitter, @cozzbie