get all combinations for a string

Question

I\'m trying to create a function in JavaScript that given a string will return an array of all possible combinations of the letters with each used at most once, starting wit

Answer 1

You could use a nasty trick and increase a counter and use its binary representation as flags:

 function combine(str){
   const result = [];
   for(let i = 1; i < Math.pow(2, str.length) - 1; i++)
      result.push([...str].filter((_, pos) => (i >> pos) & 1).join(""));
  return result;
}

Try it