function Ajax(recvType){
  var aj=new Object();
  aj.recvType=recvType ? recvType.toUpperCase() : 'HTML' //HTML XML
  aj.targetUrl='';
  aj.sendString='';
  aj.resultHandle=null;
  aj.createXMLHttpRequest=function(){
  var request=false;
  //window對(duì)象中有XMLHttpRequest存在就是非IE，包括（IE7，IE8）
  if(window.XMLHttpRequest){
    request=new XMLHttpRequest();
    if(request.overrideMimeType){
      request.overrideMimeType("text/xml");
    }
  //window對(duì)象中有ActiveXObject屬性存在就是IE
  }else if(window.ActiveXObject){
    var versions=['Microsoft.XMLHTTP', 'MSXML.XMLHTTP', 'Msxml2.XMLHTTP.7.0','Msxml2.XMLHTTP.6.0','Msxml2.XMLHTTP.5.0', 'Msxml2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP'];
    for(var i=0; i<versions.length; i++){
      try{
        request=new ActiveXObject(versions[i]);
        if(request){
          return request;
        }
      }catch(e){
        request=false;
      }
    }
  }
    return request;
  }
  aj.XMLHttpRequest=aj.createXMLHttpRequest();
  aj.processHandle=function(){
    if(aj.XMLHttpRequest.readyState == 4){
      if(aj.XMLHttpRequest.status == 200){
        if(aj.recvType=="HTML")
          aj.resultHandle(aj.XMLHttpRequest.responseText);
        else if(aj.recvType=="XML")
          aj.resultHandle(aj.XMLHttpRequest.responseXML);
      }
    }
  }
  aj.get=function(targetUrl, resultHandle){
    aj.targetUrl=targetUrl;
    if(resultHandle!=null){
      aj.XMLHttpRequest.onreadystatechange=aj.processHandle;
      aj.resultHandle=resultHandle;
    }
    if(window.XMLHttpRequest){
      aj.XMLHttpRequest.open("get", aj.targetUrl);
      aj.XMLHttpRequest.send(null);
    }else{
      aj.XMLHttpRequest.open("get", aj.targetUrl, true);
      aj.XMLHttpRequest.send();
    }
  }
  aj.post=function(targetUrl, sendString, resultHandle){
    aj.targetUrl=targetUrl;
    if(typeof(sendString)=="object"){
      var str="";
      for(var pro in sendString){
        str+=pro+"="+sendString[pro]+"&";
      }
      aj.sendString=str.substr(0, str.length-1);
    }else{
      aj.sendString=sendString;
    }
    if(resultHandle!=null){
      aj.XMLHttpRequest.onreadystatechange=aj.processHandle;
      aj.resultHandle=resultHandle;
    }
    aj.XMLHttpRequest.open("post", targetUrl);
    aj.XMLHttpRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    aj.XMLHttpRequest.send(aj.sendString);
  }
  return aj;
}

<script type="text/javascript">
  var ajax = Ajax(); // 實(shí)例化對(duì)象，默認(rèn)為 HTTP，如果傳入 XML，返回 XML 對(duì)象
  // Ajax 的 get 方法使用說(shuō)明
  /**
  * function(targetUrl, resultHandle)
  * @param string targetUrl 傳遞過(guò)去的 URL 地址
  * @param string resultHandle 回調(diào)函數(shù)，可選項(xiàng)
  */
  ajax.get('test.php?name=liruxing&email=liruxing1715@sina.com', function(data) {
    eval("var obj="+data);
    alert(obj.name);
    alert(obj.email);
  });
  // Ajax 的 post 方法使用說(shuō)明
  /**
  * function(targetUrl, sendString, resultHandle)
  * @param string targetUrl 傳遞過(guò)去的 URL 地址
  * @param string sendString 參數(shù)值
  * @param string resultHandle 回調(diào)函數(shù)，可選項(xiàng)
  */
  ajax.post('test.php', 'name=liruxing&email=liruxing1715@sina.com', function(data){
    eval("var obj="+data);
    alert(obj.name);
    alert(obj.email);
  })
  // post 第二種格式，第二個(gè)參數(shù)為 Json 格式
  ajax.post('test.php', {name:'李茹星',email:'liruxing1715@sina.com'}, function(data){
    eval("var obj="+data);
    alert(obj.name);
    alert(obj.email);
  })
</script>