Javascript - convert integer to array of bits

Question

I am trying in javascript to convert an integer (which I know will be between 0 and 32), to an array of 0s and 1s. I have looked around but couldn't find something that works..

So, if I have an integer as 22 (binary 10110), I would like to access it as:

Bitarr[0] = 0
Bitarr[1] = 1
Bitarr[2] = 1
Bitarr[3] = 0
Bitarr[4] = 1

Any suggestions? Many thanks

Answer 1

convert to base 2:

var base2 = (yourNumber).toString(2);

access the characters (bits):

base2[0], base2[1], base2[3], etc...

Answer 2

var a = 22;
var b = [];

for (var i = 0; i < 5; i++)
  b[i] = (a >> i) & 1;

alert(b);

Assuming 5 bits (it seemed from your question), so 0 <= a < 32 . If you like you can make the 5 larger, upto 32 (bitshifting in JavaScript works with 32 bit integer).

Answer 3

This should do

for(int i = 0; i < 32; ++i)
  Bitarr[i] = (my_int >> i) & 1;

Answer 4

Building up on previous answers: you may want your array to be an array of integers, not strings, so here is a one-liner:

(1234).toString(2).split('').map(function(s) { return parseInt(s); });

Note, that shorter version, (11).toString(2).split('').map(parseInt) will not work (chrome), for unknown to me reason it converts "0" s to NaN s

Answer 5

You might do as follows;

 var n = 1071, b = Array(Math.floor(Math.log2(n))+1).fill() .map((_,i,a) => n >> a.length-1-i & 1); console.log(b); 

Answer 6

SHORTESST (ES6)

Shortest (32 chars) version which fill last bits by zero. I assume that n is your number, b is base (number of output bits):

[...Array(b)].map((x,i)=>n>>i&1)

 let bits = (n,b=32) => [...Array(b)].map((x,i)=>(n>>i)&1); let Bitarr = bits(22,8); console.log(Bitarr[0]); // = 0 console.log(Bitarr[1]); // = 1 console.log(Bitarr[2]); // = 1 console.log(Bitarr[3]); // = 0 console.log(Bitarr[4]); // = 1 

Answer 7

You can convert your integer to a binary String like this. Note the base 2 parameter.

var i = 20;
var str = i.toString(2); // 10100

You can access chars in a String as if it were an array:

alert(str[0]); // 1
alert(str[1]); // 0
etc...

Answer 8

In addition, this code gives 32length array

function get_bits(value){
        var base2_ = (value).toString(2).split("").reverse().join("");
        var baseL_ = new Array(32 - base2_.length).join("0");
        var base2 = base2_ + baseL_;
        return base2;
    }
1 => 1000000000000000000000000000000
2 => 0100000000000000000000000000000
3 => 1100000000000000000000000000000

Answer 9

just for the sake of refernce:

(121231241).toString(2).split('').reverse().map((x, index) => x === '1' ? 1 << index : 0).reverse().filter(x => x > 0).join(' + ');

would give you:

67108864 + 33554432 + 16777216 + 2097152 + 1048576 + 524288 + 65536 + 32768 + 16384 + 4096 + 1024 + 512 + 256 + 128 + 8 + 1