Local Storage

  componentWillMount() {
    // Retrieve state from local storage
    const data = localStorage.getItem("state");

    // Parse JSON to JavaScript object
    const state = JSON.parse(data);

    // Set state to the retrieved JavaScript object
    this.setState(state);
  }

  componentDidMount() {
    // Add event listener that will execute code before page refresh
    window.addEventListener("beforeunload", () => {
      // Stringify the state object, so it can be saved as a text value
      const data = JSON.stringify(this.state);

      // Set localStorage item
      localStorage.setItem("state", data);
    });
  }