code.js

var url='https://query.yahooapis.com/v1/public/yql?q=select * from html where url=\''+document.getElementsByClassName('commu_name')[0].href+'\' and xpath=\'//a[@class=\"community\"][starts-with(@href,\"http://live.nicovideo.jp/watch/\")]\'&format=json&env=store://datatables.org/alltableswithkeys';
var x=new XMLHttpRequest();
x.onload=function(){
	var r=JSON.parse(x.responseText).query.results;
	if(r!==null)
		location.href=r.a.href;
};
setInterval(function(){
	x.open('GET',url);
	x.send();
},3000);