function mutation(arr) {
  var count = 0;
  var str = arr[0].toLowerCase();
  var match = arr[1].toLowerCase().split("");

  for (var i = 0; i <= match.length; i++) {
    if (str.indexOf(match[i]) !== -1) {
      count++;
    }
  }
  return (count == match.length) ? true : false;
}

mutation(["hello", "hey"]);