function ajax(url,callback,errorHandler,tag){var req=null;var respType=0;function init(){if(window.XMLHttpRequest){req=new XMLHttpRequest();req.onerror=onError;}else if(window.ActiveXObject){req=new ActiveXObject("Microsoft.XMLHTTP");}
req.onreadystatechange=onResponse;}
init();function onResponse(){if(req){if(req.readyState==4){if(req.status==200){if(callback){if(respType==0){callback(req.responseText,tag);}else if(respType==1){callback(req.responseXML,tag);}}}else{if(errorHandler){errorHandler(req.status,tag);}}}}}
function onError(){if(errorHandler){errorHandler(0,tag);}}
this.doGet=function(){req.open('GET',url,true);req.send(null);}
this.doPost=function(data){req.open('POST',url,true);req.send(data);}
this.doForm=function(data){req.open('POST',url,true);req.setRequestHeader("Content-type","application/x-www-form-urlencoded");req.send(data);}
this.doGetXml=function(){req.open('GET',url,true);req.setRequestHeader("Content-Type","text/xml");respType=1;req.send(null);}
this.doPostXml=function(data){req.open('POST',url,true);req.setRequestHeader("Content-Type","text/xml");respType=1;req.send(data);}
return this;}