CheckStrMutation.js

function CheckStrMutation(str1,str2) {
  
  var arr = [str1,str2];
  var mutationBool = true;
  
  for(var i = 0; i < arr[1].length; i++)
  {
    if(arr[0].toLowerCase().indexOf(arr[1].slice(i,i+1).toLowerCase()) === -1)
    {
      mutationBool = false;
    }
  }
  
  return(mutationBool);
}

CheckStrMutation("hello", "hey");