function returnObject(aString){
  //object initializer
  var obj = {};

    //loop through letters of string and populate keys
      for (i = 0; i < aString.length; i++) {
        obj[aString[i]] = (obj[aString[i]] || 0) + 1;
      }
    //return obj to function
    return obj;
  }
console.log(returnObject("helloooo"));