net.xmlHttp.onReadyState=function(){
  var req=this.req;
  var ready=req.readyState;
  if (ready==net.READY_STATE_COMPLETE){
    var httpStatus=req.status;
    if (httpStatus==200 || httpStatus==0){
      this.onload.call(this);
    }else{
      this.onerror.call(this);
    }
  }
}

net.xmlHttp.prototype.defaultError=function(){
  alert("error fetching data!"
    +"\n\nreadyState:"+this.req.readyState
    +"\nstatus: "+this.req.status
    +"\nheaders: "+this.req.getAllResponseHeaders());
}

下面开始写发送xmlHttp请求的代码：

default.js
//全局xmlHttp对象
var cobj;

/**//* Post begin*/
//绑定Post发送xmlHttp事件到btnTestPost
function loadTestPost()
{
   var iobj = document.getElementById("btnTestPost");
   //btnTestPost按钮监听的绑定
   var clickRouter=new jsEvent.EventRouter(iobj,"onclick");
   clickRouter.addListener(btnTestPostClick);
}
function btnTestPostClick()
{   // open参数 url, onload, params, method, contentType, onerror
    cobj = new net.xmlHttp("DefaultHandler.ashx",dealResult, "<T/>", "POST");
}
/**//* Post end*/

/**//* Get begin*/
//绑定Get发送xmlHttp事件到btnTestGet
function loadTestGet()
{
   var iobj = document.getElementById("btnTestGet");
   //btnTestGet按钮监听的绑定
   var clickRouter=new jsEvent.EventRouter(iobj,"onclick");
   clickRouter.addListener(btnTestGetClick);
}
function btnTestGetClick()
{   //  open参数 url, onload, params, method, contentType, onerror
    cobj = new net.xmlHttp("DefaultHandler.ashx?T=1",dealResult, null, "GET");
}
/**//* Get end*/