get-cookie.js

function getCookie(key) {
  try {
    if (typeof key === 'string' && key.length > 0 && document.cookie.length > 0) {
      let cookieRegExp = new RegExp(key, 'g');
      let ary = document.cookie.split(';');
      let isCookie;
      if (ary.length > 0) {
        isCookie = ary.filter(function (cookie) {
          return cookieRegExp.test(cookie) === true;
        });
      }
      if (isCookie.length === 1) {
        let cookieAry = isCookie[0].split('=');
        return cookieAry.length === 2 ? cookieAry[1].trim() : undefined;
      }
    } else {
      return undefined;
    }
  } catch (e) {
    console.log(e);
  }
}