jquery ajax传值替空

jquery ajax传值为空
帮看看怎么我传的参数是空的

$("#bt").blur(function(){
var newnum=$("#bt").val();
var bookid=$("#bookid").val();
 $.ajax({
       type:"post",
       url:"go.action",
       data:"newnum="+(newnum)+""&"bookid="+(bookid)+"",
       success:function(data){
   
      }
      });
       
});

[解决办法]
 $.ajax({
       type:"post",
       url:"go.action",
       data:"newnum="+newnum+"&bookid="+bookid,
       success:function(data){
    
      }
      });