CI - JS (Cookie)

var originUser = function(){
      if(typeof origin_cookie != "undefined"){
        // If everything was ok, you should see the cookie via your console
    // From here, you could inspect, and decide, what to do with corresponding user
    console.log(origin_cookie);
      }
};

var cookie_asset = document.createElement('script');
cookie_asset.setAttribute("type","text/javascript");
cookie_asset.setAttribute("src", 'http://mainsite.com/cookie/status');
cookie_asset.onload  = originUser;
document.getElementsByTagName("head")[0].appendChild(cookie_asset);