zhangmyihua / lesson-9 Goto Github PK

Hi Yihua,
Thanks for your sharing!

I have questions about line 21 in the App.js file, why unsubscribeFromAuth can be initialised without having var/let/const.
And why this initiation is not placed in the constructor()?
Thanks!

Remember to delete yarn.lock and node_modules and run yarn install and yarn upgrade --latest to fix the automated errors.

App crashes with latest version of firebase

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.
in App (at App.test.js:7)

In App.js:

componentDidMount() {
    this.unsubscribeFromAuth = auth.onAuthStateChanged(user => {
      this.setState({ currentUser: user });
    });
  }