how to check if value exists from value?

if I have the following values

0 - a
1 - b
2 - c
4 - d
8 - e
16 - f

if i get the value 17, how would i know that values b and f are in that values, some for the others as these can be mixed together by adding, so bd value would be 6

>Solution :

Convert your value to binary format. For example 17 => 10001. Then select only 1’s. You can make for loop starts from ‘a’ to ‘z’. Increase characters +1 then convert to character.

This is sample code:

function foo(num) {
  if (num == 0)
    return 'a';

  const binaryNum = (num >>> 0).toString(2);

  function nextChar(c) {
      return String.fromCharCode(c.charCodeAt(0) + 1);
  }

  var converted = '';
  var asci = 'b';
  for(var i=binaryNum.length-1; i>=0; --i) {
      if (binaryNum.charAt(i) == '1')
          converted+=asci;
      asci = nextChar(asci);
  }
  return converted;
}

console.log(foo(17));
console.log(foo(0));
console.log(foo(6));
console.log(foo(28));

Output is:

bf
a
bd
def

Note that ‘bd’ is 5.