$.extend({ 
        　　 add:function(a,b){return a+b;},
            bad:function(a,b){return a-b;}
        }); 
        $.fn.extend({
            loading:function(flg){
                if(flg){
                    $(this).show();
                }else{
                    $(this).hide();
                }
            }
        })
        console.log($.add(3,4));
        console.log($.bad(3,4));
        $(‘#div‘).loading(false);