JavaScript中的Ajax

兼容地获得XMLHttpRequest对象：

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1. var xhr = null; 
2. if(window.XMLHttpRequest){  //非IE浏览器 
3.       xhr = window.XMLHttpRequest; 
4. }else if(window.ActiveXObject){ //IE浏览器 
5.       try{           //高版本，受msxml3.dll+支持 
6.              xhr = new ActiveXObject("Msxml2.XMLHTTP"); 
7.       }catch(e){ 
8.              try{       // 低版本，msxml2.6以下版本使用 
9.                     xhr = new ActiveXObject("Microsoft.XMLHTTP"); 
10.              }catch(e){  
11.                     alert("IE浏览器无法创建ActiveXObject对象！"); 
12.              } 
13.       } 
14. } 

var xhr = null;if(window.XMLHttpRequest){  //非IE浏览器      xhr = window.XMLHttpRequest;}else if(window.ActiveXObject){  //IE浏览器      try{           //高版本，受msxml3.dll+支持             xhr = new ActiveXObject("Msxml2.XMLHTTP");      }catch(e){             try{       // 低版本，msxml2.6以下版本使用                    xhr = new ActiveXObject("Microsoft.XMLHTTP");             }catch(e){                     alert("IE浏览器无法创建ActiveXObject对象！");             }      }}

AJAX处理函数：

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1. xhr.open("POST",url,true); 
2. xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); 
3. xhr.onreadystatechange=stateChangeHandler; 
4. xhr.send();  //var name="clf";   xhr.send(name); 
5. function stateChangeHandler(){ 
6.       if(xhr.readystate==4&&xhr.status==200){ 
7.             var obj = document.getElementById("targetDiv"); 
8.         obj.innerHTML = xhr.responseText; 
9.       } 
10. }