title: $.ajax send twice, event.preventDefault not usable?
body: <p>I just learning javascript and jquery now I have a problem using jquery datatables.</p>
  
  <p>My Data were post twice to php. I don´t know how to implement event.preventDefault on my script and return false wont work.</p>
  
  <pre><code>olistorderproduktdatatable = $("#listorderprodukttable").dataTable({
      "bJQueryUI": true, "bPaginate": false, "bFilter": true, "bInfo": false, "bAutoWidth": true, "sDom": 'Rlfrtip', 
      "bServerSide": true,
      "sSearch" :"Filter",
      "bDestroy": true,
      "sAjaxSource": "share/content/helper/datatablelistorderprodukt.php" 
  });
  
  $('#listorderprodukttable tbody').delegate("tr", "click", rowClickAddPosition);
  
  function rowClickAddPosition(){
      //Welche Zeile wurde selektiert und ID herausfiltern 
     if (hlr)
        $("td:first", hlr).parent().children().each(function(){$(this).removeClass('markrow');});
     hlr = this;
     $("td:first", this).parent().children().each(function(){$(this).addClass('markrow');});
  
     // You can pull the values out of the row here if required
     var a = $("td:first", this).text();
     var b = $("td:eq(1)", this).text();
  
     selectedRow      = a;  //ID der Zeile WICHTIGE VARIABLE!!!
  
      //Abfrage ob ID leer ist, also ob es überhaupt Einträge gibt.
     if(selectedRow != "No matching records found"){
          $.ajax({
              type : 'POST',
              url : 'share/content/helper/orderaddposition.php',
              cache: false,
              data: {
                  SelectedProdukt : selectedRow,
                  BestellID       : BestellID
              },
              success: function(data) {
                  callbackaddposition();
              }
          });
      }
  }
  </code></pre>
  
  <p>I don´t know how to catch the event?</p>