Understanding a React App, Folder Structuring, Basics etc.

Example of code for Understanding a React App

If you’re new to React or just getting started with your first project there is some things you need to know for Understanding a React App, it can be overwhelming to figure out how to structure your files and understand the basics. In this guide, we’ll break down the folder structure of a React app and cover the essential concepts you need to know to get up and running.

From components and state management to routing and API calls, we’ll cover all the fundamentals you need to build a solid foundation in React development.

Whether you’re a beginner or an experienced developer looking to refresh your knowledge, this guide will help you gain a deeper understanding of how to build robust and scalable React applications.

Create React App

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  1. First, make sure you have Node.js installed on your machine. You can download it from the official website: https://nodejs.org/
  2. Open your terminal or command prompt and navigate to the directory where you want to create your React app.
  3. Once you’re in the desired directory, run the following command to create a new React app:
npx create-react-app my-app

This will create a new directory called “my-app” (you can replace “my-app” with any name you like) and initialize a new React project inside it.

  1. Once the project has been created, navigate into the project directory using the following command:
cd my-app
  1. You can now start the development server and run your app using the following command:
npm start

This will launch the development server and open your app in a new browser window.

That’s it! You now have a basic React app up and running. You can start editing the code in the “src” directory to customize your app.

Folder Structuring

The folder structure for a new React app can vary depending on the specific needs of the project, but a commonly used and recommended structure is:

  1. PUBLIC: This folder contains the HTML file and other assets that are publicly accessible, such as images, fonts, and favicon.
  2. SRC: This folder is where you will write your React code. It typically includes the following subfolders:
  3. COMPONENTS: This folder contains the reusable components that make up the UI of your app.
  4. PAGES: This folder contains the components that represent the different pages of your app.
  5. SERVICES: This folder contains the code that interacts with external services, such as APIs.
  6. UTILS: This folder contains utility functions and helpers that can be reused throughout your app.
  7. STYLES: This folder contains the CSS or Sass files that define the styles for your app.
  8. ASSETS: This folder contains static assets such as images, videos, and audio files that are used in your app.
  9. CONFIG: This folder contains configuration files for your app, such as environment variables and third-party library configurations.

By following this folder structure, you can organize your codebase in a way that is easy to navigate and maintain, which is essential for scaling your app as it grows.

Understanding the Hooks

Hooks are a feature introduced in React 16.8 that allow you to use state and other React features without writing a class component. They are functions that let you “hook into” React state and lifecycle features from functional components.

Here are some of the most commonly used hooks in React:

  1. useState(): This hook allows you to add state to your functional components. It returns a state value and a function to update that value.
  2. useEffect(): This hook allows you to add lifecycle methods to your functional components. It lets you run side effects (such as fetching data or updating the DOM) after the component has rendered.
  3. useContext(): This hook allows you to access the nearest context object in your component’s tree. It’s a way to pass data through the component tree without having to pass props down manually at every level.
  4. useReducer(): This hook allows you to manage state using a reducer function, similar to how you would manage state in a Redux store.
  5. useCallback(): This hook is used for performance optimization. It memoizes a function so that it only gets re-created when its dependencies change.
  6. useMemo(): This hook is used for performance optimization as well. It memoizes a value so that it only gets re-calculated when its dependencies change.
  7. useRef(): This hook returns a mutable ref object that can be used to store a value across re-renders.

These are just a few examples of the many hooks available in React. They provide a simple and consistent way to add powerful features to your functional components.

Understanding Components and Props

In React, a component is a self-contained unit of code that can be reused throughout your application. Components can be thought of as building blocks that you can use to construct your user interface. There are two main types of components in React: functional components and class components.

Functional components are the simplest type of component in React. They are just plain JavaScript functions that return a piece of JSX code. Here’s an example of a functional component:

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

In this example, the Greeting component takes a single prop called name, and uses it to render a greeting to the user. The props argument is an object that contains all of the props that were passed to the component.

Class components are a bit more complex than functional components, but they also offer more functionality. Class components are defined as ES6 classes that extend the React.Component class. Here’s an example of a class component:

class Counter extends React.Component {
  constructor(props) {
    this.state = { count: 0 };

  handleClick() {
    this.setState({ count: this.state.count + 1 });

  render() {
    return (
        <h1>Count: {this.state.count}</h1>
        <button onClick={() => this.handleClick()}>Increment</button>

In this example, the Counter component is a class component that maintains its own state using the this.state object. It also defines a handleClick method that updates the state when the user clicks the “Increment” button. Finally, it uses the render method to return a piece of JSX code that displays the current count and a button to increment it.

To pass props to a component, you simply include them as attributes when you render the component. Here’s an example of rendering the Greeting component from earlier with a name prop:

<Greeting name="Alice" />

In this example, the name prop is set to “Alice”, so the component will render a greeting that says “Hello, Alice!”.

Similarly, you can pass props to a class component like this:

<Counter />

In this example, no props are passed to the Counter component, so it will initialize its state to { count: 0 } and render a count of 0.


In React, a router is a library that allows you to handle client-side routing within your application. Client-side routing means that the routing is handled by the browser, rather than by the server. This allows you to create a more responsive and interactive user interface, as changes to the URL can trigger updates to the UI without requiring a page reload.

There are several router libraries available for React, but one of the most popular is React Router. React Router is a declarative routing library that allows you to define routes and navigate between them using a simple API.

Here’s an example of how to use React Router to define some routes:

import { BrowserRouter as Router, Route, Switch } from 'react-router-dom';
import Home from './Home';
import About from './About';
import Contact from './Contact';

function App() {
  return (
        <Route exact path="/" component={Home} />
        <Route path="/about" component={About} />
        <Route path="/contact" component={Contact} />

In this example, we import BrowserRouter, Route, Switch, and three components: Home, About, and Contact. We then define a set of routes using the Route component, and wrap them in a Switch component to ensure that only one route is matched at a time. Finally, we wrap the routes in a BrowserRouter component to provide the router context to our application.

Each Route component takes two props: path and component. The path prop defines the URL path that should match this route, and the component prop specifies the component that should be rendered when this route is matched.

For example, if the user navigates to the /about URL, the About component will be rendered. If the user navigates to the /contact URL, the Contact component will be rendered, and so on.

React Router also provides several other features, such as URL parameters, nested routes, and programmatic navigation. These features allow you to create complex routing behavior within your application, while still keeping the routing logic within your client-side code.

Overall, the router is an essential tool for creating dynamic, interactive user interfaces in React, and React Router is one of the most popular and widely used routing libraries available for React.

More Introduction to React

React is a popular JavaScript library for building user interfaces. It was developed by Facebook and released to the public in 2013. React is based on the concept of components, which are reusable building blocks that you can use to create complex user interfaces.

One of the key features of React is its use of a virtual DOM (Document Object Model). The virtual DOM is a lightweight copy of the actual DOM, which is the browser’s representation of the HTML document.

When you update the state of a component in React, it re-renders the virtual DOM, compares it to the previous version, and updates only the parts of the actual DOM that have changed. This makes React very fast and efficient, even for large and complex user interfaces.

React also has a number of other features that make it a powerful tool for building user interfaces. For example, React allows you to use JSX, which is a syntax extension that allows you to write HTML-like code directly in your JavaScript. JSX is not required to use React, but it can make your code more concise and easier to read.

React also has a strong ecosystem of third-party libraries and tools. For example, React Router is a popular library for adding client-side routing to React applications, while Redux is a popular library for managing application state.

In addition to its features and ecosystem, React has a large and active community of developers who contribute to its development and share their knowledge and expertise through blogs, forums, and other resources. This community has helped to make React one of the most popular and widely used tools for building user interfaces on the web.

Overall, React is a powerful and flexible tool for building user interfaces, with a wide range of features and a strong ecosystem of tools and resources. Whether you’re building a simple website or a complex web application, React can help you to create a fast, efficient, and scalable user interface.