title: how to compare a fbjs variable with fbjs undefined?
body: <p>i have an alert in fbjs which returns undefined but when i am comparing a fbjs variable with underined it does not work...</p>
  
  <pre><code>var params = document.getElementById('ques_form').serialize();
      user_answer = params.radio;
      if(user_answer=="undefined")
      {
          alert("please select any option");
          return false;
      }
  </code></pre>