I don't know why the Mutations algorithm is not working

I need help with the Mutations algorithm problem. Can anyone give me a hint or idea on why my evaluation is not equating to true when it’s true etc? Any help is appreciated it.

function mutation(arr) {

  let containsLetters = false;    

  let str1 = arr[0].toLowerCase().split('');

  let str2 = arr[1].toLowerCase().split('');


  for(let i =0; i < str2.length; i++){


          containsLetters = true;




  return containsLetters;


mutation(["floor", "for"])

There are other things that need work, but try looking into how includes works.

Thank you. That was my next step. Trying to really understand this function.