The components you've seen so far in this book have been classes that extend the base
Component class. It's time to learn about functional components in React. In this section, you'll learn what a pure functional component is by implementing one. Then, we'll cover setting default property values for stateless functional components.
A functional React component is just what it sounds like—a function. Picture the
render() method of any React component that you've seen. This method, in essence, is the component. The job of a functional React component is to return JSX, just like a class-based React component. The difference is that this is all a functional component can do. It has no state and no lifecycle ...