function $() {//好东西是一定要拿来用的
  var elements = new Array();
  for (var i = 0; i < arguments.length; i++) {
    var element = arguments[i];
    if (typeof element == 'string')
      element = document.getElementById(element);
    if (arguments.length == 1)
      return element;
    elements.push(element);
  }
  return elements;
}

function getXMLHttpRequest(){       //获取Ajax实例
    var xmlHR=null;
    if(window.ActiveXObject){
        try {xmlHR=new ActiveXObject("Msxml2.XMLHTTP");}
        catch(e){try{xmlHR=new ActiveXObject("Microsoft.XMLHTTP");}
        catch(e){}}
    }else if(window.XMLHttpRequest){
        xmlHR=new XMLHttpRequest();
        if(xmlHR.overrideMimeType)
        xmlHR.overrideMimeType('text/xml');
        }else{alert("Create XMLHttpRequest object false!");return false;}
    return xmlHR;
}

function doAjax(method,url,params,errFun,statFun,rsFun){
    var ajax=getXMLHttpRequest();
    ajax.onreadystatechange=function(){
        if(ajax.readyState == 4){ 
      if(ajax.status == 200) eval(rsFun);
            else eval(errFun);
        }else eval(statFun);}
    if(method=="get"){url=url+"?"+params;params=null;}
    ajax.open(method,url,true);
    ajax.setRequestHeader("cache-control","no-cache");          //要紧,清除缓存
    if(method=="post") ajax.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    ajax.send(params);
}