title: TypeError .val() is not a function on my selected answer on Javascript
body: <p>I'm trying to check if the answer selected is correct, if so, then it should add + 1 to my user score. 
  But I don't understand why my code doesn't work. Could you please help me where the bug or did I miss something else?  </p>
  
  <pre><code> function loadNextQuestion () {
    var selectOption = document.querySelector('input[type=radio]:checked');
    if (selectOption.val() == questions[answer]) {
      ++userScore;
    } else if (selectOption) {
      ++currentQuestionNum;
      loadQuestion();
      loadQuestionNum();
    } else {
      alert("Please pick an answer.");
    }
  };
  $("#nextButton").click(loadNextQuestion);
  });
  </code></pre>