ajax封装

 1 var createXHR=function(){
 2       if(typeof XMLHttpRequest!="undefined"){
 3           return new XMLHttpRequest();
 4       }else if(typeof ActiveXObject!="undefined"){
 5           var version=["MSXML2.XMLHttp.6.0",
 6                        "MSXML2.XMLHttp.3.0",
 7                        "MSXML2.XMLHttp"];
 8           for(var i=0,len=version.length;i<len;i++){
 9               try{
10                   return new ActiveXObject(version[i]);
11               }catch(ex){
12                   //跳过
13               }
14           }
15       }else{
16           throw new Error("您的浏览器不支持ajax");
17       }
18 };
19 
20 //名值对转化为字符串
21 function params(data){
22     var arr=[];
23     for(var i in data){
24         arr.push(encodeURIComponent(i)+"="+encodeURIComponent(data[i]));
25     }
26     return arr.join("&");
27 }
28 
29 //封装ajax
30 function ajax (obj){
31     var xhr=createXHR();
32     obj.url = obj.url+"?rand="+Math.random()+"&"+params(obj.data);    
33     if(obj.method === "get"){  //get请求
34         obj.url = obj.url+(obj.url.indexOf("?")==-1 ? "?" : "&")+params(obj.data);
35     }
36     
37     if(obj.async==true){  //异步请求
38        xhr.onreadystatechange=function(){
39            if(xhr.readyState == 4){
40                 callback();
41            }
42        };
43     }
44     xhr.open(obj.method,obj.url,obj.async);
45     
46     if(obj.method === "post"){   //post请求
47         xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
48         xhr.send(params(obj.data));
49     }else{
50        xhr.send(null);
51     }
52     
53     if(obj.async == false){
54         callback();
55     }
56     function callback(){
57         if(xhr.status == 200){
58             obj.success(xhr.responseText);  //回调函数传递参数
59         }else{
60             alert("获取数据错误！错误代号："+xhr.status+",错误信息："+xhr.statusText);
61         }
62     }
63 }
64 
65 //调用ajax
66 var object={
67         method:"get",
68         url:"demo.php",
69         async:false,
70         data:{
71             name:"liu",
72             age:25
73             },
74         success:function (text){
75                    console.log(text);
76                 }
77         };
78 document.addEventListener("click",function(){
79     console.log(ajax(object));
80 },false);