Implement drop-down box based on jQuery_jquery

         $(function(){
                 $('#add').click(function(){
                var $options = $('#select1 option:selected');
                       $options.appendTo("#select2");
              });
                 $('#remove').click(function(){
                var $options = $('#select2 option:selected');
                      $options.appendTo("#select1");
              });
                 $('#add_all').click(function(){
                var $options = $('#select1 option');
                       $options.appendTo("#select2");
              });
                 $('#remove_all').click(function(){
                var $options = $('#select2 option');
                      $options.appendTo("#select1");
              });
                 $('#select1').dblclick(function(){
              var $options = $("option:selected",this); //Get the selected option
                       $options.appendTo('#select2');
              });
                  $('#select2').dblclick(function(){
              var $options = $("option:selected",this); //Get the selected option
                       $options.appendTo('#select1');
              });
         });