Bootstrap

npx create-react-app converter
cd converter
yarn start

App is now running at http://localhost:3000.

Goal

We're going to extend our Euro-to-$BTC functionality to support more cryptocurrencies.

You can start from your own App from last week, or simply git checkout start to have an app ready to work with.

Our Product Owner foresees a demand in conversion for other cryptocurrencies: extract the convertion logic into a <Converter /> component that takes a cryptoName and a exchangeRate. We can drop the crash to zero after 5 seconds functionality.
Add a second converter to our app, one for Ethereum $ETH with a 1.2 exchangeRate. Add as many as you want.
Our design team finds the lack of a title per <Converter /> a usuabillity problem. Allow the <Converter /> component to render some custom markup to render it at the top of the component.
Monetization is key. Add an alert to warn the user about our freemium conversion model after 5 convertions are performed in any of the components in our app.
We need a way to let our users become Premium Members. Implement a Become Premium button that removes the just implemented alert and adds a 💎 Premium conversion message.

Add a number input with a label, "Euros".
Extract the input into a separate component called <Amount /> that takes a name (eg. "Euros") prop.
(Optional) If it is not already, convert <Amount /> into a class-based component.
Teach <Amount /> input to show a red outline for negative amounts.
Make <Amount /> a controlled component (ie. pass it its value as a prop).
Add a second, read-only <Amount /> component that shows $BTC instead of Euros; use this function to get the exchange rate:
```
function exchangeRate() {
  return Math.random() * 10000;
}
```
Use setTimeout to make the $BTC price crash to zero after 5 seconds of inactivity.
Use React.createContext() to provide a dark/light theme toggle.