All you need to know to start working with react

Requirements:

• Beginner with basic knowledge of HTML, CSS, js and using terminal.

• Node.js should be installed in your system - Install

• A code editor for writing codes. ( I prefer VScode)

Create a react app:

• Create a folder - start-react

• Go to folder location in terminal using - cd start-react

• Run command npx create-react-app . , this command initializes the current folder as a react app.

Folder Structure:

• node_modules is a folder that contains all the packages and their respective dependencies that are required or used in the project.

• Dependencies are external libraries or modules that have been used or are needed to run the react application.

  • package.json has a list of all the dependencies used in the project.

  • package.lock.json contains information on specific versions of those dependencies.

• public folder contains some files of which index.html is the most important file and it has only one div present in its body with id = "root" . This div is the main container where all react code will be rendered.

• src the folder is the most important folder which you will deal with most of the time.

  • It has three main files index.js , index.css and App.js . All files other than this can be deleted and we can create project-related files when needed.

  • index.js the file is the root file that connects our react codes to the index.html present in public folder using the div with id = "root" .

  • App.js is nothing but the main or first component of the react app which is rendered.

  • This code of index.js will make it more understandable to you.

      import React from 'react';
      import ReactDOM from 'react-dom/client';
      import './index.css';
      import App from './App';
    
      const root = ReactDOM.createRoot(document.getElementById('root'));
      // this root refers to the div in the index.html of public folder
    
      root.render(
        <React.StrictMode>
          <App />
        </React.StrictMode>
      );
    
      // render is a method in React which renders the react components
    

  • Do this to your src folder:

    • Remove all the files inside src folder except index.js , App.js and index.css .

    • Update the index.js as follows

        import React from 'react';
        import ReactDOM from 'react-dom/client';
        import './index.css';
        import App from './App';
      
        const root = ReactDOM.createRoot(document.getElementById('root'));
        root.render(
          <React.StrictMode>
            <App />
          </React.StrictMode>
        );
      

    • Update the App.js as follows

        import React from 'react';
      
        const App = () => {
          return (
            <div>
            Hello Learners!
            </div>
          )
        }
      
        export default App
      

• Now open the terminal, go to the location of start-react directory the location in which node_modules is present and run npm start .

• This will open a page on your default browser.

  

• Great! Now you're set up to work on react and you have created your react app.

What did we learn?

• In this lesson, we learned how to set up our system to create a react app.

• Then we understood what is the folder structure.

  • node_modules where all the codes for packages and dependencies are present.

  • package.json contains the list of dependencies whereas package.lock.json contains information about the versions of the dependencies used in the app.

  • public folder contains index.html which has one div with id = "root" where all the react code is rendered.

  • The most important folder is the src , has three main files index.js , index.css and App.js .

Next Lesson?

• In the upcoming lessons I will teach you about how to write html in react, how to use javascript variables to change html easily, concept of props and more.

Till then, bye!