Book Image

The React Workshop

By : Brandon Richey, Ryan Yu, Endre Vegh, Theofanis Despoudis, Anton Punith, Florian Sloot
5 (1)
Book Image

The React Workshop

5 (1)
By: Brandon Richey, Ryan Yu, Endre Vegh, Theofanis Despoudis, Anton Punith, Florian Sloot

Overview of this book

Are you interested in how React takes command of the view layer for web and mobile apps and changes the data of large web applications without needing to reload the page? This workshop will help you learn how and show you how to develop and enhance web apps using the features of the React framework with interesting examples and exercises. The workshop starts by demonstrating how to create your first React project. You’ll tap into React’s popular feature JSX to develop templates and use DOM events to make your project interactive. Next, you’ll focus on the lifecycle of the React component and understand how components are created, mounted, unmounted, and destroyed. Later, you’ll create and customize components to understand the data flow in React and how props and state communicate between components. You’ll also use Formik to create forms in React to explore the concept of controlled and uncontrolled components and even play with React Router to navigate between React components. The chapters that follow will help you build an interesting image-search app to fetch data from the outside world and populate the data to the React app. Finally, you’ll understand what ref API is and how it is used to manipulate DOM in an imperative way. By the end of this React book, you’ll have the skills you need to set up and create web apps using React.
Table of Contents (20 chapters)
Preface

The Unmount Lifecycle

The unmount lifecycle lives outside of the main lifecycle, as it only comes into play when a component is removed from the DOM. This lifecycle is also far more limited, as the only lifecycle method it contains is componentWillUnmount().

componentWillUnmount()

componentWillUnmount() exists solely to perform and react to the component being removed from the DOM, and then is eventually removed entirely from existence. While it sounds a bit dramatic, it's important to note that this is what happens when a component is otherwise completely destroyed. It takes no arguments, and there are some caveats about using it.

The code for componentWillUnmount() might look something like this:

class App extends Component {
  componentWillUnmount() {
    alert("I've been removed!");
  }
  render() {
    return (<div className="App">Hello World!</div>);
 ...