What is ReactJS?

ReactJS is a JavaScript library used to build User Interfaces (UI). It significantly decreases the code with its components, states (i.e., hooks), etc.

Creating a React App

Open your terminal in the directory where you would like to create your application. Run this command to create a React application named my-react-app:

npx create-react-app my-react-app

OR, you can directly make your application without specifying a name, like this:

npx create-react-app .

In this case, all files will be kept in the current directory.

Note: When choosing a folder name, make sure there are no spaces or capital letters because of npm naming restrictions.

Once the base application is created, if a folder is specified, you just have to enter the folder. You can use this command to enter:

cd directory-name

Then just start up the application with this command:

npm start

and you are good to go!

Hello World

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<h1>Hello, world!</h1>);

In this, we are just putting an <h1> tag in a div with id 'root'. That's it! In the div with id 'root', everything will be rendered. We can also change it from 'root' to something else, as we are just getting an element and putting HTML in it.