title: Serialize form data return empty string
body: <p>I apologize if my question is duplicate. I studied all same issue and did the following:
  1. remove all disabled input field.
  2. check if there any id is repeated. No id is repeated.
  3. Every form field has a name.
  But the following code return empty string:</p>
  
  <pre><code>$('#answer_sheet_btn').click(function(e){
          e.preventDefault();
          console.log( $( this ).serializeArray() );
  
    });
  </code></pre>
  
  <p>Here is my form:</p>
  
  <pre><code>&lt;form method="post" action="/wordpress/wp-admin/admin.php?page=active-exam&amp;amp;exam_id=1" id="question_paper"&gt;
          &lt;p&gt;&lt;/p&gt;&lt;table class="bix-tbl-container" style="height: 40px" border="0" width="533" cellspacing="0" cellpadding="0"&gt;
  &lt;tbody&gt;
  &lt;tr&gt;
  &lt;td class="bix-td-qtxt" valign="top"&gt;If 60 J of energy are available for every 15 C of charge, what is the voltage?&lt;/td&gt;
  &lt;/tr&gt;
  &lt;/tbody&gt;
  &lt;/table&gt;&lt;p&gt;&lt;/p&gt;
      &lt;input name="opt1[]" type="checkbox" value="1"&gt;60 V &lt;input name="opt1[]" type="checkbox" value="2"&gt;4 V  &lt;input name="opt1[]" type="checkbox" value="3"&gt;15 V &lt;input name="opt1[]" type="checkbox" value="4"&gt;.25 V    &lt;hr&gt;
  
      &lt;p&gt;Which resistive component is designed to be temperature sensitive?&lt;/p&gt;
      &lt;input name="opt2[]" type="checkbox" value="1"&gt;Rheostat &lt;input name="opt2[]" type="checkbox" value="2"&gt;Thermistor   &lt;input name="opt2[]" type="checkbox" value="3"&gt;Potentiometer    &lt;input name="opt2[]" type="checkbox" value="4"&gt;Photoconductive cell &lt;hr&gt;
  
  &lt;input type="hidden" name="q_ids" value="1,2"&gt;
  &lt;p class="submit"&gt;
      &lt;input type="submit" name="answer_sheet" id="answer_sheet_btn" class="button-primary" value="submit"&gt;
  &lt;/p&gt;
  
  &lt;/form&gt;
  </code></pre>
  
  <p>This kill my day. I think I am doing some stupid type mistake. Please point it out. </p>
  
  <p>N.B: I tried removing the hidden field </p>
  
  <pre><code>&lt;input type="hidden" name="q_ids" value="1,2"&gt;
  </code></pre>