opening

    
 <div id="dialog" style="display: none">Lorem ipsum dolor sit amet, consectetur adipiscing elit...</div>
 <button onclick="dialog.open()">Open Dialog</button>
 <script>
     var dialog = $("#dialog").dialog({
         autoOpen: false,
         opening: function (e) {
             alert('The opening event is fired.');
         },
         opened: function (e) {
             alert('The opened event is fired.');
         }
     });
 </script>