function writeCookie(name, value, hours){
	 var expire = "";
	 if(hours != null){
	  expire = new Date((new Date()).getTime() + hours * 3600000);
	  expire = "; expires=" + expire.toGMTString();
	 }
	 domain = "; domain=" + "ifeng.com";
	 path = "; path=" + "/";
	 document.cookie = name + "=" + escape(value) + expire + domain + path ;
}

function QueryString(fieldName){
	  var urlString = document.location.search;
	  if(urlString != null)
	  {
		   var typeQu = fieldName+"=";
		   var urlEnd = urlString.indexOf(typeQu);
		   if(urlEnd != -1)
		   {
				var paramsUrl = urlString.substring(urlEnd+typeQu.length);
				var isEnd =  paramsUrl.indexOf('&');
				if(isEnd != -1)	
				{	
					 paramsUrl = paramsUrl.substring(0, isEnd);	
				}	
				writeCookie(fieldName,paramsUrl,24);
				return paramsUrl;
		   }
		   else
		   return null;
	  }
	 else
	 return null;
}

var url = QueryString("_from");