Function to wasy work with cookies (source: https://www.sitepoint.com/how-to-deal-with-cookies-in-javascript/)

cookies.js

function createCookie(name, value, expires, path, domain) {
  var cookie = name + "=" + escape(value) + ";";

  if (expires) {
    // If it's a date
    if(expires instanceof Date) {
      // If it isn't a valid date
      if (isNaN(expires.getTime()))
       expires = new Date();
    }
    else
      expires = new Date(new Date().getTime() + parseInt(expires) * 1000 * 60 * 60 * 24);

    cookie += "expires=" + expires.toGMTString() + ";";
  }

  if (path)
    cookie += "path=" + path + ";";
  if (domain)
    cookie += "domain=" + domain + ";";

  document.cookie = cookie;
}

function getCookie(name) {
  var regexp = new RegExp("(?:^" + name + "|;\s*"+ name + ")=(.*?)(?:;|$)", "g");
  var result = regexp.exec(document.cookie);
  return (result === null) ? null : result[1];
}