Simple JS Cookie Helper Class

cookieManager.js

/***
 * Cookie Manager Class w/Static Methods
 */
export default class CookieManager {
  /***
   * Check if value exists in cookie that is a csv list.
   *
   * @param {string} key
   * @param {string} value
   * @return {bool}
   */
  static setCookieCheckListValueExists(key, value) {
    let listOfValues = CookieManager.getCookie(key);
    listOfValues = listOfValues ? listOfValues.split(',') : [];
    return listOfValues.contains(value);
  }

  /***
   * Add a value if unique to list of values save as cookie.
   *
   * @param {string} key
   * @param {string} value
   */
  static setCookieAddUniqueListValue(key, value) {
    // Get array of profiled pages from cookie
    let listOfValues = CookieManager.getCookie(key);
    listOfValues = listOfValues ? listOfValues.split(',') : [];


    // test if exists
    if (!listOfValues.contains(value)) {
      // add if doesn't
      listOfValues.push(value);
      CookieManager.setCookie(key, listOfValues.join(','));
    }
  }

  /***
   * Simple copypasta cookie set value.
   *
   * @param {string} key
   * @param {string} value
   * @param expiration_days
   */
  static setCookie(key, value, expiration_days = 30) {
    let expires_date = new Date();
    expires_date.setDate(expires_date.getDate() + expiration_days);
    let expires = "expires="+ expires_date.toUTCString();
    document.cookie = key + "=" + value + ";" + expires + ";path=/";
  }

  /***
   * Simple copyapasta cookie get value by key.
   *
   * @param {string} key
   * @return {string}
   */
  static getCookie(key) {
    let name = key + "=";
    let decodedCookie = decodeURIComponent(document.cookie);
    let ca = decodedCookie.split(';');
    for(let i = 0; i <ca.length; i++) {
      let c = ca[i];
      while (c.charAt(0) == ' ') {
        c = c.substring(1);
      }
      if (c.indexOf(name) == 0) {
        return c.substring(name.length, c.length);
      }
    }
    return "";
  }
}

This is not intended as complex data storage, but simple strings and array strings . For anything beyond a small data sets local storage or database is far superior. More a proof of concept for small or trivial projects. Copy paste and get / set cookies.