title: jquery date and time calculation firefox NaN
body: <p>I am trying to calculate days between certain date, I am using date and time.  On chrome works fine, but on Firefox gives me  "NaN", haven't test it on Ie, but I think it will be same result.
                 </p>
  
  <pre><code>            &lt;form action="" enctype="multipart/form-data" id="userForm" method="post"&gt;
              &lt;table border="0"&gt;
              &lt;tbody&gt;            
                &lt;tr class="rsform-block rsform-block-paemimodata"&gt;
                  &lt;td&gt;Delivery Date (*)&lt;/td&gt;
                  &lt;td&gt;&lt;input type="text" class="datepicker rsform-input-box hasDatepicker" id="paemimodata" name="form[paemimodata]" size="20" value="2013-05-15"&gt;&lt;/td&gt;
  
                &lt;/tr&gt;
                &lt;tr class=""&gt;
                  &lt;td&gt;Time (Hours) (*)&lt;/td&gt;
                  &lt;td&gt;&lt;select class="rsform-select-box" id="paemimolaikas" name=""&gt;&lt;option value="01"&gt;01&lt;/option&gt;
                      &lt;option value="02"&gt;02&lt;/option&gt;
                      &lt;option value="03"&gt;03&lt;/option&gt;
                      &lt;option value="04"&gt;04&lt;/option&gt;
                      &lt;option value="05"&gt;05&lt;/option&gt;
                      &lt;option value="06"&gt;06&lt;/option&gt;
                      &lt;option value="07"&gt;07&lt;/option&gt;
                      &lt;option value="08"&gt;08&lt;/option&gt;
                      &lt;option value="09"&gt;09&lt;/option&gt;
                      &lt;option value="10"&gt;10&lt;/option&gt;
                      &lt;option value="11"&gt;11&lt;/option&gt;
                      &lt;option value="12"&gt;12&lt;/option&gt;
                      &lt;option value="13"&gt;13&lt;/option&gt;
                      &lt;option value="14"&gt;14&lt;/option&gt;
                      &lt;option value="15"&gt;15&lt;/option&gt;
                      &lt;option value="16"&gt;16&lt;/option&gt;
                      &lt;option value="17"&gt;17&lt;/option&gt;
                      &lt;option value="18"&gt;18&lt;/option&gt;
                      &lt;option value="19"&gt;19&lt;/option&gt;
                      &lt;option value="20"&gt;20&lt;/option&gt;
                      &lt;option value="21"&gt;21&lt;/option&gt;
                      &lt;option value="22"&gt;22&lt;/option&gt;
                      &lt;option value="23"&gt;23&lt;/option&gt;
                      &lt;option value="24"&gt;24&lt;/option&gt;
                    &lt;/select&gt;
          &lt;/td&gt;
                &lt;/tr&gt;  
                &lt;tr class=""&gt;
                  &lt;td&gt;Time ( minutes )&lt;/td&gt;
                  &lt;td&gt;&lt;select class="rsform-select-box" id="paemimolaikasmin" name=""&gt;
                      &lt;option value="05"&gt;05&lt;/option&gt;
                      &lt;option value="10"&gt;10&lt;/option&gt;
                      &lt;option value="15"&gt;15&lt;/option&gt;
                      &lt;option value="20"&gt;20&lt;/option&gt;
                      &lt;option value="25"&gt;25&lt;/option&gt;
                      &lt;option value="30"&gt;30&lt;/option&gt;
                      &lt;option value="35"&gt;35&lt;/option&gt;
                      &lt;option value="40"&gt;40&lt;/option&gt;
                      &lt;option value="45"&gt;45&lt;/option&gt;
                      &lt;option value="50"&gt;50&lt;/option&gt;
                      &lt;option value="55"&gt;55&lt;/option&gt;
                      &lt;option value="00"&gt;00&lt;/option&gt;
                    &lt;/select&gt;
                 &lt;/td&gt;
  </code></pre>
  
  <p>    
                      Return Date (<em>)
                      
                        
                    
                    
                      Time ( hours ) (</em>)
                      
                          01
                          02
                          03
                          04
                          05
                          06
                          07
                          08
                          09
                          10
                          11
                          12
                          13
                          14
                          15
                          16
                          17
                          18
                          19
                          20
                          21
                          22
                          23
                          24
                        
                      
                    
                    
                      Time ( minutes ) 
                      
                          05
                          10
                          15
                          20
                          25
                          30
                          35
                          40
                          45
                          50
                          55
                          00
                        
                      
                    <br>
                  
                </p>
  
  <pre><code>        &lt;/form&gt;
              &lt;/xmp&gt;
  </code></pre>
  
  <p>Java Script</p>
  
  <pre><code>                &lt;pre&gt;
  
  
              jQuery(function ($) {
  
              function coundays () {
  
  
              var starter = $('#paemimodata').val();
  
              var starterhour = $('#paemimolaikas').val();
              var startermin = $('#paemimolaikasmin').val();
  
  
              var ender =  $('#grazinimodata').val();
  
              var enderhour = $('#grazinimolaikas').val();
              var endermin = $('#grazinimolaikasmin').val();
  
              var fullstarter = starter + ' ' +  starterhour + ':' + startermin + ':00';
  
              var fullender = ender + ' ' + enderhour + ':' + endermin + ':00';
  
                  var start = new Date(fullstarter);
                  var end = new Date(fullender);
              var diff = new Date(end - start);
              var days = diff/1000/60/60/24;
  
  
              alert(days);
  
              };
  
  
               coundays ();
  
  
                 $('#userForm').on('change', function() {
                      coundays ();
  
                });
  
  
  
  
  
  
              });
  
  
                  &lt;/pre&gt;
  </code></pre>
  
  <p>Js fidlle</p>
  
  <p><a href="http://jsfiddle.net/dezignas/j2HGw/13/" rel="nofollow">http://jsfiddle.net/dezignas/j2HGw/13/</a></p>
  
  <p>What I am doing wrong here ?</p>