Jquery ajax执行顺序 返回自定义错误信息(实例讲解)

1.多个ajax 在一个function中的执行顺序

由于jquery中的ajax的async默认是true(异步请求),如果想一个ajax执行完后再执行另一个ajax, 需要把async=false就可以了.

. 代码如下:

function testajax(){
            var username = $("#txtusername").val();
            $.ajax(
            {
                url: "ajaxcheckusername.htm",
                async: false,
                success: function (data) {
                    alert(data);
                }
            });
            alert('test');
            $.ajax({
                url: "ajaxhandler.ashx",
                async: false,
                data: "username=" + username,
                success: function (data) {
                    $("#pajax").html(data);
                },
                error: function (msg) {
                    alert(msg.responsetext);
                }
            });
        }

2. 返回自定义错误

 

设置 statuscode = 500,

触发ajax的错误(error), 在接收到数据显示自定义信息

. 代码如下:

error: function (msg) {
                    alert(msg.responsetext);
                }

 

 context.response.statuscode = 500;
 context.response.write("请输入用户名");

. 代码如下:

string susername = context.request.querystring["username"];
            if (!string.isnullorempty(susername))
            {
                context.response.write(string.format("hello {0}!", susername));
            }
            else
            {
                context.response.statuscode = 500;
                context.response.write("请输入用户名");
            }