function mutation(arr) {
  var arr1 = arr[0].toLowerCase().split('');
    var arr2 = arr[1].toLowerCase().split('');
    var count = 0;
    for (let i =0; i < arr2.length; i++) {
        if(arr1.indexOf(arr2[i]) > -1 ) {
            count++;
        }
    }
  return count == arr2.length
}

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