```
function mutation(arr) {
  
  var str1=arr[0].toLowerCase();
  var str2= arr[1].toLowerCase();
  
  var arr1 =[];


  for(var i = 0; i<str2.length; i++) {
    arr1.push (str1.indexOf(str2[i]) );
   }
  
  for (var j=0;j<arr1.length;j++) {
    if (arr1[j] !== -1) {
      return true;
    } else {
      return false;
    }
    
             
  }

}

mutation(["hello", "oen"]);
```