Tell us what’s happening:
i’ve spent like 5 hour but still don’t know where i did mistake ,pls help

Your code so far

function mutation(arr) {
  var count=0;
  for (i=0; i< arr[1].length;i++)
    if (arr[0].indexOf(arr[1][i],0) >= 0 )
      count +=1 ;
 if (count == arr[1].length)
      return true;
  else return false;
mutation(["hello", "hey"]);

Your browser information:

Your Browser User Agent is: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.186 Safari/537.36.

Link to the challenge:


What part isn’t working? What behavior are experiencing that isn’t occurring? What steps have you taken to try to fix it? What have your debugging efforts taught you?


Your toLowerCase isn’t doing anything because you’re not assigning the value to anything.

  arr[0] = arr[0].toLowerCase();
  arr[1] = arr[1].toLowerCase();


OMg, :smile: thunder cat :smile: thanks man , you’re my savior