title: jQuery: the checked property is undefined on change event
body: <p>I see many questions on this topic but none have resolved my issue. </p>
  
  <p><strong>Trouble is:</strong> I have a checkbox and need the new value of the checked property when a user clicks it. </p>
  
  <p>I have tried the different event attachers like on.("change" .. and .change(function() .. but always it returns "undefined". 
  I have also tested (with alerts) if the assignment to the variables was done more then once, but they dont. Just once.</p>
  
  <p>Please consider the script and tell me if you know what I am doing wrong. Or if i should post more info. </p>
  
  <pre><code>$(document).ready(function () {
          $('#invoice_list :checkbox').on('change', function () {
              var _invoice_id;
              var _payed;
              var _sent;
              $(this).parent().siblings().each(function () {
                  if ($(this).hasClass('name?ajax_invoice_id')) {
                      _invoice_id = $(this).text();
                  }
                  if ($(this).hasClass('name?ajax_payed')) {
                      _payed = $(this).children(':checkbox').prop('checked');
                  }
                  if ($(this).hasClass('name?ajax_sent')) {
                      _sent = $(this).children(':checkbox').prop('checked');
                  }
              });
              alert('invoice_id: ' + _invoice_id + '\r\npayed: ' + _payed + '\r\nsent: ' + _sent);
          });
      });        
  </code></pre>
  
  <p>If i check the "payed" checkbox this is the result no matter the new value (same goes for "sent"): <a href="http://i.stack.imgur.com/m2Iac.png" rel="nofollow">localhost says</a></p>
  
  <p><a href="http://i.stack.imgur.com/JFYKx.png" rel="nofollow">html from razor view</a></p>
  
  <pre><code>&lt;tbody class="clickable"&gt;
                      &lt;tr&gt;
                          &lt;td class="name?ajax_invoice_id"&gt;85&lt;/td&gt;
                          &lt;td&gt;31-10-2015 16:54:27&lt;/td&gt;
                          &lt;td&gt;31-10-2015 00:00:00&lt;/td&gt;
                          &lt;td&gt;31-10-2015 00:00:00&lt;/td&gt;
                          &lt;td&gt;4800,00&lt;/td&gt;
                          &lt;td&gt;6000,00&lt;/td&gt;
                          &lt;td&gt;1200,00&lt;/td&gt;
                          &lt;td&gt;25,00 %&lt;/td&gt;
                          &lt;td&gt;1&lt;/td&gt;
                          &lt;td&gt;6,00&lt;/td&gt;
                          &lt;td&gt;800,00&lt;/td&gt;                            
                          &lt;td class="name?ajax_sent"&gt;&lt;input data-val="true" data-val-required="The Sendt field is required." id="Collection_0__Sent" name="Collection[0].Sent" type="checkbox" value="true" /&gt;&lt;input name="Collection[0].Sent" type="hidden" value="false" /&gt;&lt;/td&gt;
                          &lt;td class="name?ajax_payed"&gt;&lt;input data-val="true" data-val-required="The Betalt field is required." id="Collection_0__Payed" name="Collection[0].Payed" type="checkbox" value="true" /&gt;&lt;input name="Collection[0].Payed" type="hidden" value="false" /&gt;&lt;/td&gt;
                      &lt;/tr&gt;
                      &lt;tr&gt;
                          &lt;td class="name?ajax_invoice_id"&gt;36&lt;/td&gt;
                          &lt;td&gt;25-10-2015 18:54:35&lt;/td&gt;
                          &lt;td&gt;25-10-2015 00:00:00&lt;/td&gt;
                          &lt;td&gt;25-10-2015 00:00:00&lt;/td&gt;
                          &lt;td&gt;6400,00&lt;/td&gt;
                          &lt;td&gt;8000,00&lt;/td&gt;
                          &lt;td&gt;1600,00&lt;/td&gt;
                          &lt;td&gt;25,00 %&lt;/td&gt;
                          &lt;td&gt;1&lt;/td&gt;
                          &lt;td&gt;8,00&lt;/td&gt;
                          &lt;td&gt;800,00&lt;/td&gt;                            
                          &lt;td class="name?ajax_sent"&gt;&lt;input data-val="true" data-val-required="The Sendt field is required." id="Collection_1__Sent" name="Collection[1].Sent" type="checkbox" value="true" /&gt;&lt;input name="Collection[1].Sent" type="hidden" value="false" /&gt;&lt;/td&gt;
                          &lt;td class="name?ajax_payed"&gt;&lt;input data-val="true" data-val-required="The Betalt field is required." id="Collection_1__Payed" name="Collection[1].Payed" type="checkbox" value="true" /&gt;&lt;input name="Collection[1].Payed" type="hidden" value="false" /&gt;&lt;/td&gt;
                      &lt;/tr&gt;
          &lt;/tbody&gt;
  </code></pre>