Number(x).toString(2)

  (x).toString(2)

128, 64, 32, 16, 8, 4, 2, 1

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Let's decompose 231.

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231 >= 128; That's a 1 in first position. 1

231 - 128 = 103 >= 64; We have a one in the second position. 11.

103 - 64 = 39 >= 32; One in the third position. 111.

39 - 32 = 7 < 16; Zero in the fourth position. 1110.

7 < 8; Zero in the fifth place. 11100

7 >= 4; 111001

7 - 4 = 3 >= 2; 1110011

3 - 2 = 1 >= 1; Final result: 11100111. Enjoy your cats :)

All you have to do is integer division by two and keep the remainder. You don't even need to know the powers of two.

Here's an example with 137.

  137 % 2 = 1
  68  % 2 = 0
  34  % 2 = 0
  17  % 2 = 1
  8   % 2 = 0
  4   % 2 = 0
  2   % 2 = 0
  1   % 2 = 1

Final result: 10001001

You can use a similar method to convert the fractional part of a float, but with multiplication.