jquery的ajax请求方法：
$.ajax({
type: "GET",
dateType:"html",
url: "index.html",
error: function(msg) { alert("error"); },
complete: function(msg) { alert("complete"); },
success: function(msg) { alert("success"); }
});
jquery中各个事件执行顺序如下：
1.ajaxStart(全局事件)
2.beforeSend
3.ajaxSend(全局事件)
4.success
5.ajaxSuccess(全局事件)
6.error
7.ajaxError (全局事件)
8.complete
9.ajaxComplete(全局事件)
10.ajaxStop(全局事件)
