Ajax的方法和使用代码 

 1 //1.创建Ajax对象，已经封装好的函数：
 2 function createXHR(){
 3     if (typeof XMLHttpRequest != "undefined"){
 4         return new XMLHttpRequest();
 5     } else if (typeof ActiveXObject != "undefined"){
 6         if (typeof arguments.callee.activeXString != "string"){
 7             var versions = ["MSXML2.XMLHttp.6.0", "MSXML2.XMLHttp.3.0",
 8                             "MSXML2.XMLHttp"],
 9                 i, len;
10     
11             for (i=0,len=versions.length; i < len; i++){
12                 try {
13                     var xhr = new ActiveXObject(versions[i]);
14                     arguments.callee.activeXString = versions[i];
15                     return xhr;
16                 } catch (ex){
17                     //skip
18                 }
19             }
20         }
21     
22         return new ActiveXObject(arguments.callee.activeXString);
23     } else {
24         throw new Error("No XHR object available.");
25     }
26 }
27 
28 //直接引用
29 
30 var xhr = createXHR(); 
31        
32 //2.请求状态监控
33 
34 xhr.onreadystatechange = function(event){
35     if (xhr.readyState == 4){
36         if ((xhr.status >= 200 && xhr.status < 300) || xhr.status == 304){
37             alert(xhr.responseText);
38         } else {
39             alert("Request was unsuccessful: " + xhr.status);
40         }
41     }
42 };
43 //3.连接服务器（方法，文件名，异步传输）
44 xhr.open("get", "example.txt", true);
45 //4.发送请求
46 xhr.send(null);

 

posted @ 2016-08-24 23:30  Scott-Jeremy  阅读(218)  评论(0)  编辑  收藏  举报