Function to return all permutations of a string

permutations.js

function showAllPermutations(mixyString){
  var unMixy, permutations = [];

  popAndLock = function(string, root){
    var i;
    if(root == null){
      root = ""
    }

    for(i=0; i<string.length; i+=1){
      startCharacter = string[i];
      leftover = string.slice(0,i).concat(string.slice(i+1));

      if(leftover.length > 1){
        popAndLock(leftover, root+startCharacter);
      }
      else{
        permutations.push(root+startCharacter+leftover);
      }
    }
  }

  unMixy = mixyString.split("").sort().join("");
  popAndLock(unMixy);

  return permutations;
}