Category: ReactJS

Getting started with ReactJS

Setting up a local environment is recommended way to learn ReactJS because the local setup allows you to complete the tutorial using your choice of editor, use the latest JavaScript features, provides a nice developer experience, and optimizes your app for production.

Let’s start with creating a new ReactJS application.

Create React App

Creating React App is a comfortable environment for learning and building an application in React.

There are few prerequisites for creating a React app as follows,

  • Node.js >= 14.0.0
  • npm >= 5.6

If above requirements are satisfied, you can run the following command to create a new react application,

npx create-react-app my-react-app

You can change my-react-app to anything you want to name your app.

The create-react-app command will set up everything you need to run a React application. Now you are ready to run your first real React application! Go to your application directory using the following command,

cd my-react-app

Now, run the following command inside your application directory to run your application,

npm start

It will compile your application and open it in the new browser window or tab. If not, you can open your browser and write localhost:3000 in the address bar. Your application will look like screenshot below,

If you check your command window, it will show the following output,

You can see that command window is also providing command to create a production build for your application.

Using ReactJS in the HTML File

Now that we know what ReactJS is, we can start with different usage of ReactJS. If you don’t know what ReactJS is, read the ReactJS introduction.

In this article, we will learn to use ReactJS directly in the HTML file. There are some prerequisites to adding ReactJS script inside the HTML code. We need to include the following three javascript in the head section of the HTML file.

  • ReactJS
  • ReactDom
  • Babel

The first two allow us to write ReactJS code in our JavaScripts, and Babel will allow to write JSX syntax and ES6 in older browsers.

Example

Let’s see an example of using ReactJS in the HTML file,

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <script src="https://unpkg.com/react@18/umd/react.development.js" crossorigin></script>
    <script src="https://unpkg.com/react-dom@18/umd/react-dom.development.js" crossorigin></script>
    <script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>
  </head>
  <body>
    <div id="example"></div>
    <script type="text/babel">
      function Hello() {
        return <h1>Hello World!</h1>;
      }
      ReactDOM.render(<Hello />, document.getElementById('example'))
    </script>
  </body>
</html>

This way, we can use ReactJS for testing purposes. But for production use, we have to set up a React environment.

ReactJS Introduction

ReactJS is one of the most popular JavaScript front-end libraries for building user interfaces with a strong foundation. It has a robust and rapidly growing developer community and a declarative, efficient, and flexible library for building reusable UI components. It is an open-source, component-based front-end library responsible only for the application view layer. 

ReactJS is one of the most popular JavaScript front-end libraries for building user interfaces with a strong foundation. It has a robust and rapidly growing developer community and a declarative, efficient, and flexible library for building reusable UI components. It is an open-source, component-based front-end library responsible only for the application view layer. 

Initially, it was developed by Jordan Walke, a software engineer at Facebook and maintained by Facebook. Later, it was used in other Facebook products like WhatsApp & Instagram. Facebook implemented ReactJS in its newsfeed section in 2011, but it was released to the public in May 2013.

The main objective of ReactJS is to develop interactive User Interfaces (UI) with the help of virtual DOM (JavaScript object) to improve application performance because the JavaScript virtual DOM is faster than the regular DOM because, it only changes individual DOM elements instead of reloading complete DOM every time. It uses component and data patterns that improve readability and helps to maintain larger apps.

The components are the heart of all React applications. These component are used to make a React application. Each component is responsible for outputting a small, reusable piece of HTML code and can be nested with other components to allow complicated applications.