Greeting.js

class Greeting extends Component {
  hello = id => console.log(`hello world! - ${id}`);

  componentDidMount() {
    const id = shortid.generate();
    setInterval(e => this.hello(id), 1000);
  }

  componentWillUnmount() {
    console.log("Greeting unmounted...");
  }

  render() {
    return (
      <div>
        <Link to="/main">Go to Main Page</Link>
      </div>
    );
  }
}