// BAD: this runs three functions
                              
                            
                          
                          

                            

                              
                                // before it realizes there's nothing
                              
                            
                          
                          

                            

                              
                                // in the selection
                              
                            
                          
                          

                            

                              $("#nosuchthing").slideUp();
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              
                                // Better
                              
                            
                          
                          

                            

                              var $mySelection = $("#nosuchthing");
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              if ( $mySelection.length ) {
                            
                          
                          

                            

                               
                            
                          
                          

                            

                                $mySelection.slideUp();
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              }
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              
                                // BEST: add a doOnce plugin
                              
                            
                          
                          

                            

                              jQuery.fn.doOnce = function( func ){
                            
                          
                          

                            

                               
                            
                          
                          

                            

                                this.length && func.apply( this );
                            
                          
                          

                            

                               
                            
                          
                          

                            

                                return this;
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              }
                            
                          
                          

                            

                               
                            
                          
                          

                            

                              $("li.cartitems").doOnce(function() {

                            
                          
                          

                            

                               
                            
                          
                          

                            

                                // make it ajax! \o/

                            
                          
                          

                            

                               
                            
                          
                          

                            

                              });