自定义ajax

  1 (function(){
  2     var Ajax=function(params){
  3         this.config={
  4             url:"",
  5             type:"get",
  6             async:true,
  7             dataType:"json",
  8             contentType:"application/x-www-form-urlencoded; charset=UTF-8",
  9             data:{}
 10         };
 11         this.start(params);
 12     };
 13     var xhr = null;
 14     Ajax.init=function(params){
 15         new Ajax(params);
 16     };
 17     Ajax.prototype={
 18         constructor: Ajax,
 19         createXHR:function(){
 20             if(typeof XMLHttpRequest!=‘undefined‘){
 21                 return new XMLHttpRequest();
 22             }else if(typeof ActiveXObject!=‘undefined‘){
 23                 if(typeof arguments.callee.activeXString!=‘string‘){
 24                     var versions=["MSXML2.XMLHttp.6.0","MSXML2.XMLHttp.3.0","MSXML2.XMLHttp"],i,len;
 25                     for(i=0,len=versions.length;i<len;i++){
 26                         try{
 27                             new ActiveXObject(versions[i]);
 28                             arguments.callee.activeXString=versions[i];
 29                             break;
 30                         }catch(ex){
 31 
 32                         }
 33                     }
 34                 }
 35                 return new ActiveXObject(arguments.callee.activeXString);
 36             }else{
 37                 throw new Error("No XHR object available.");
 38             }
 39         },
 40         start:function(params){
 41             xhr=new this.createXHR();
 42             if(params.url){
 43                 this.config.url=params.url;
 44             }else{
 45                 throw new Error("url cannot be null!");
 46             }
 47             if(params.type){
 48                 this.config.type=params.type;
 49             }
 50             if(params.async){
 51                 this.config.async=params.async;
 52             }
 53             if(params.dataType){
 54                 this.config.dataType=params.dataType;
 55             }
 56             if(params.data){
 57                 this.config.data=params.data;
 58             }
 59             if(params.success){
 60                 this.config.success=params.success;
 61             }
 62             if(params.fail){
 63                 this.config.fail=params.fail;
 64             }
 65             if(params.beforeSend){
 66                 params.beforeSend();
 67             }
 68 
 69             var complete=function(){
 70                 if(xhr.readyState==4){
 71                         if((xhr.status>=200&&xhr.status<300)||xhr.status==304){
 72                             if(params.success){
 73                                 params.success(xhr.responseText);
 74                             }
 75                         }else{
 76                             if(params.fail){
 77                                 params.fail();
 78                             }else{
 79                                 throw new Error("Request was unsucessful:"+xhr.status);
 80                             }
 81                         }
 82                 }
 83             }
 84 
 85             if(this.config.dataType=="json"||this.config.dataType=="JSON"){//非跨域
 86                 if((this.config.type=="GET")||(this.config.type=="get")){
 87                     for(var item in this.config.data){
 88                         this.config.url=addURLParam(this.config.url,item,this.config.data[item]);
 89                     }
 90                     xhr.onreadystatechange=complete;
 91                     xhr.open(this.config.type,this.config.url,this.config.async);
 92                     xhr.send(null);
 93                 }
 94                 if(this.config.type=="POST"||this.config.type=="post"){
 95                     xhr.addEventListener(‘readystatechange‘,complete);
 96                     xhr.open(this.config.type,this.config.url,this.config.async);
 97                     if(params.contentType){
 98                         this.config.contentType=params.contentType;
 99                     }
100                     xhr.setRequestHeader("Content-Type",this.config.contentType);
101                     xhr.send(serialize(this.config.data));
102                 }
103             }else if((this.config.dataType=="jsonp")||(this.config.dataType=="JSONP")){//跨域
104                 if((this.config.type=="GET")||(this.config.type=="get")){//jsonp只能进行get请求跨域
105                     if(!params.url||!params.callback){
106                         throw new Error("params is illegal!");
107                     }else{
108                         this.config.callback=params.callback;
109                     }
110                     //创建script标签
111                     var cbName=‘callback‘;
112                     var head=document.getElementsByTagName(‘head‘)[0];
113                     this.config[this.config.callback]=cbName;
114                     var scriptTag=document.createElement(‘script‘);
115                     head.appendChild(scriptTag);
116 
117                     //创建jsonp的回调函数
118                     window[cbName]=function(json){
119                         head.removeChild(scriptTag);
120                         clearTimeout(scriptTag.timer);
121                         window[cbName]=null;
122                         params.success&&params.success(json);
123                     };
124                     //超时处理
125                     if(params.time){
126                         scriptTag.timer=setTimeout(function(){
127                             head.removeChild(scriptTag);
128                             params.fail&&params.fail({message:"over time"});
129                             window[cbName]=null;
130                         },params.time);
131                     }
132                     this.config.url=this.config.url+"?callback="+cbName;
133                     for(var item in this.config.data){
134                         this.config.url=addURLParam(this.config.url,item,this.config.data[item]);
135                     }
136                     scriptTag.src=this.config.url;
137                 }
138             }else{
139                 throw new Error("dataType is error!");
140             }
141         }
142     }
143     function addURLParam(url,name,value){
144         url+=(url.indexOf("?")==-1 ? "?" : "&");
145         url+=encodeURIComponent(name)+"="+encodeURIComponent(value);
146         return url;
147     }
148     //序列化函数
149     function serialize(data){
150         var val="";
151         var str="";
152         for(var item in data){
153             str=item+"="+data[item];
154             val+=str+‘&‘;
155         }
156         return val.slice(0,val.length-1);
157     }
158     window["Ajax"]=Ajax;
159 })();

 1 window.onload=function(){
 2         Ajax.init({
 3         url:"http://localhost:8080/AjaxCROSTest/data.json",
 4         type:"get",
 5         dataType:"jsonp",
 6         data:{"help":"me","to":"die"},
 7         callback:"callback",
 8             time:"1000",
 9         beforeSend:function(){
10             //...
11         },
12         success:function(data){
13             //...
14         },
15         fail:function(ex){
16             console.log(ex);
17         }
18     });
19 }