Please tell me what is wrong with my code . i didnt find any problem

Tell us what’s happening:

Your code so far

function mutation(arr) {
  
  var a=arr[0].toLowerCase().split("");
  var b=arr[1].toLowerCase();
  for(var i=0;i<b.length;i++){
    if(a.indexOf(b[i].split(""))!==-1){ return true;}
    return false;
  }
}

mutation(["hello", "hey"]);```
**Your browser information:**

Your Browser User Agent is: ```Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:57.0) Gecko/20100101 Firefox/57.0```.

**Link to the challenge:**
https://www.freecodecamp.org/challenges/mutations