Method get

third_party/subscriptions-project/swg.js:18737–18756

* @param {string} key * @param {boolean=} useLocalStorage * @return {!Promise<?string>}

(key, useLocalStorage = false)

   * @return {!Promise<?string>}
   */
  get(key, useLocalStorage = false) {
    if (!this.values_[key]) {
      this.values_[key] = new Promise((resolve) => {
        const storage = useLocalStorage
          ? this.win_.localStorage
          : this.win_.sessionStorage;
        if (storage) {
          try {
            resolve(storage.getItem(storageKey(key)));
          } catch (e) {
            // Ignore error.
            resolve(null);
          }
        } else {
          resolve(null);
        }
      });
    }
    return this.values_[key];
  }

  /**
   * @param {string} key