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Introduction do React.js


So you've decided to dip your toes into the world of React, huh? Great choice! React is a popular JavaScript library for building user interfaces, and it's an essential tool for any front-end developer to have in their toolkit.

What is React?


React is a JavaScript library for building user interfaces. It was developed by Facebook, and has gained popularity due to its declarative approach to building UI, which makes it easier to reason about and manage complex UI interactions.

In React, you define components, which are reusable pieces of UI that accept input (called "props") and return a tree of elements that describe what should be displayed on the screen. When the input changes, React updates the UI automatically to reflect the new state of the application.

Getting started with React


Ready to start building with React? Here's what you'll need:

To get started with React, you'll also need to include the React library in your project. There are several ways to do this, but the most common is to include it via a script tag in your HTML file:


  <script src="https://unpkg.com/react@16/umd/react.development.js"></script>
  <script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
  

This will give you access to the React library and all of its functions and methods.

Creating your first React component


Now that you have everything you need to get started, let's create your first React component! A React component is a JavaScript function that returns a React element, which is a lightweight description of what should be rendered.

The React element describes the UI that you want to render, but it doesn't actually do the rendering itself. To actually render the element to the screen, you'll need to use the ReactDOM library, which you included in your project earlier. You can do this by calling the `ReactDOM.render()` function and passing it the element you want to render, as well as the DOM node where you want to render it:


  ReactDOM.render(element, document.getElementById('root'));
  

For example, let's create a simple component that displays a greeting message:


  function Greeting(props) {
    return <h1>Hello, {props.name}!</h1>;
  }

  ReactDOM.render(
   <Greeting name="React" />,
  document.getElementById('root')
  );
  

This component accepts a prop called `name`, which is passed in as an attribute when the component is used. The component then returns a React element that displays a greeting message with the `name` prop included in the message. When you call the `ReactDOM.render()` function, the component is rendered to the DOM node with the ID of `root`, which you'll need to define in your HTML file like this:


  <div id="root"></div>
  

And that's it! You've just created your first React component. You can now use this component anywhere in your project, and it will always display the same greeting message with the same name. You can also pass in different props to customize the greeting message for each use of the component.

Next steps


Congratulations on making it this far! You now have a solid understanding of what React is and how it works. From here, you can start building more complex applications by creating additional components and combining them together in meaningful ways. You can also start learning about advanced React concepts like state, lifecycle methods, and performance optimization.

Book recommendations


React: Up & Running

This book is written by Tom Occhino and Jordan Walke, two of the original developers of React. It's a great resource for learning about the fundamentals of React, as well as more advanced concepts like JSX, state, and performance optimization. It also includes practical examples and case studies to help you apply what you've learned to real-world situations.

Learning React

Written by Kirupa Chinnathambi, this book is a comprehensive guide to learning React, covering everything from the basics of components and JSX to advanced topics like routing and data management. It includes plenty of examples and exercises to help you practice what you've learned, and it's suitable for both beginners and experienced developers looking to improve their skills.

React: The Complete Guide

This book, written by Maximilian Schwarzm├╝ller, is a comprehensive guide to learning React, covering everything from the basics of components and JSX to advanced topics like performance optimization, testing, and deployment. It includes plenty of examples and exercises to help you practice what you've learned, and it's suitable for both beginners and experienced developers looking to improve their skills.

React Quickly

Written by Azat Mardan, this book is a fast-paced guide to learning React, covering everything from the basics of components and JSX to advanced topics like routing and data management. It includes plenty of examples and exercises to help you practice what you've learned, and it's suitable for both beginners and experienced developers looking to improve their skills.

Fullstack React

Written by Anthony Accomazzo, this book is a comprehensive guide to building full-stack web applications with React, covering everything from the basics of components and JSX to advanced topics like data management, testing, and deployment. It includes plenty of examples and exercises to help you practice what you've learned, and it's suitable for both beginners and experienced developers looking to improve their skills.

There are plenty of resources available to help you on your journey, including the official React documentation, online tutorials, and community forums. Don't be afraid to ask for help or advice, and happy coding!