This JavaScript module lets you store information on the client with localStorage or sessionStorage with a fallback to cookies.

CookieMaster.js

// import CookieMaster
// create an instance, e.g., ```cm = new CookieMaster("localStorage");```
// run ```cm.checkStoreKey(yourKey, yourValue);``` to store your information, providing that the key doesn't already exist

class CookieMaster {
  constructor(type) {
    // type = "sessionStorage" or "localStorage"; latter is default
    this.type = type || "localStorage";
  }

  checkStoreKey(key, value) {
    if (window.storageAvailable(this.type)) {
      if (this.type === "sessionStorage" && sessionStorage.getItem(key) === null) {
        sessionStorage.setItem(key, value);
        return true;
      }
      return false;
    } else if (this.type === "localStorage" && localStorage.getItem(key) === null) {
        localStorage.setItem(key, value);
        return true;
    } else {
      const allKeys = this.getCookieKeys();
      if (allKeys.indexOf(key) === -1) {
        this.setACookie(key, value);
        return true;
      }
      return false;
    }
  }

  setACookie(cookieKey, cookieValue) {
    document.cookie = `${cookieKey}=${cookieValue}`;
  }

  getCookieKeys() {
    return document.cookie.split(";").map(item => item.split("=")[0].trim());
  }

  storageAvailable(type) {
    try {
      var store = window.type;
    } catch (e) {
    } finally {
      if (store === undefined) {
        return false;
      } else {
        return true;
      }
    }
  }
}

export default CookieMaster;