ajax实际应用（1）客户端部分

function getAjaxObject()
{
 var ajax = null;
 if(window.XMLHttpRequest)
 {
  ajax = new XMLHttpRequest();
 }
 else if(window.ActiveXObject)
 {
  ajax = new ActiveXObject("Microsoft.XMLHTTP");
 }
 return ajax;
}

function test()
{
 var ajax=getAjaxObject();
 ajax.onreadystatechange=function()
 {
  if (ajax.readyState==4)
  {
   var xmlDoc=ajax.responseXML;
   var root = xmlDoc.documentElement;
   for(i=0;i<root.childNodes.length;i++)
   {
    alert(root.childNodes[i].getAttribute("name"));
   }

  }
 };  
 ajax.open("get","http://localhost/test.do",false);   //用true异步,不会有卡的感觉
 ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); 
 ajax.send();
}