IE和FF中event的兼容解决办法

        function aaa(){
            var evt = getEvent();
            alert(evt.clientX);
            return false;
        }
        
        function getEvent() //同时兼容ie和ff的写法
        {
                if(document.all)   return window.event;   
                func=getEvent.caller;       
                while(func!=null){
                    var arg0=func.arguments[0];
                    if(arg0)
                    {
                      if((arg0.constructor==Event || arg0.constructor ==MouseEvent) || (typeof(arg0)=="object" && arg0.preventDefault && arg0.stopPropagation))
                      {
                      return arg0;
                      }
                    }
                    func=func.caller;
                }
                return null;
        }