DAY_THREE_README.md

Day III

Focus (Day III)

• Be able to explain and implement a React Higher Order Component to conditionally render protected content to the screen.

Daily Setup (Day III)

• To start off today, your application should still be structured like yesterday, but now it should have a working search bar, comment input, and like icon.
• Those aren't necessary, however, for what you will be doing today. You can still work on today's part of this project even if you aren't completely done with yesterday's portion.

Description (Day III)

• Today you will be building a "Higher Order Component" (HOC)
• The HOC will not let users see the posts until they have logged in. (Our login system for this will be faked using LocalStorage).
• The job of the HOC will be to render a login page if the user is not logged in, then render the posts after the user is logged in.

Tasks (Day III)

• Create a <PostsPage /> component in your components/PostsContainer directory.

  • You'll have to move a lot of what is rendered in app.js to this new component
  • In app.js, render the PostsPage component.
  • Make sure the app working as it was before since it has been re-factored now.
  • This is to ensure that we clean up our App component a little bit before we re-factor it to be wrapped up in an HOC

• Building the High Order Component

  • Create a directory called authentication
  • Inside that directory create a HOC called withAuthenticate. This is where all of the magic is going to happen.
  • This component should be able to take in a component as an argument, and it will return a class component.
  • Inside of withAuthenticate's render method, you'll want to return the Component that gets passed into it.
  • Be sure to export.
  • Head over to App.js and import in our new withAuthenticate Higher Order Component.
  • Set a new const called ComponentFromWithAuthenticate, and set it's value to the HOC invoked, with PostsPage passed in.
  • Inside App, you should now render ComponentFromWithAuthenticate in place of PostsPage.
  • If this worked correctly, then everything should render as it used to.
  • withAuthenticate will look a lot like this when you're done setting it up.

const withAuthenticate = App =>
  class extends React.Component {
    render() {
      return <App />;
    }
  };

• Build out the LoginPage component. You can design it how you like

  • In your components directory, create a directory called Login and add a new file called Login.js.
  • There should be a username input, a password input, and a Login button.
  • The component should invoke the login function in Login.js when a user logs in.
  • This login function should set a username on localStorage. You'll need to check local storage to see if a user is logged in.
  • Be sure to force the page to reload when a user logs in so that our component un-mounts and mounts again.

• Extending the functionality of the HOC to conditionally render the LoginPage or the App

  • First, we need to change our withAuthenticate HOC to return a second function that will take in a second component (which will be the LoginPage). This will look like a "double arrow" function - const withAuthenticate = PostsPage => LoginPage => {}.
  • In App.js, we can now invoke the HOC function twice (which is called currying). The first time it's invoked, pass in PostsPage. The second time, pass in LoginPage (which you'll need to import here). ie - export default higherOrderComp(FirstComponent)(SecondComponent)
  • Inside of the class component that the inner function in withAuthenticate returns, we need to add a constructor to hold our state data.
  • On state we need a loggedIn boolean flag.
  • In componentDidMount we need to check localStorage to see if a user is logged in, and setState accordingly.
  • Inside of the render function we will check if a user is logged in from the state boolean flag
  • If a user is logged in we will return the <PostsPage />, else we will return the <LoginPage>

Stretch Problems (Day III)

• Now that you have a user set in localStorage, go ahead and use that username when a user posts a comment to make it so the logged in user is the one commenting on the posts.

• Styled-Components

  • Watch this video about styled-components in its entirety.
  • Head over to the Styled-Components docs and learn about the library.
  • Once you feel like you've got a good grasp of this concept, go ahead and start converting your components into styled-components.
  • Try and make this thing as beautiful as possible

• Deploy your Instagram clone to netlify and share it in the #show-it-off channel.