Setting Up a React Environment Using Npm, Babel and Webpack

In fact, these tools are not required to use React and but in order to get the most out of the features of ES6, JSX and bundling, we need them. In this blog post, we are going to see how to setup a React development environment.

Let’s start from scratch

Create a new folder ‘react-hello-world’ and initialize it with npm.

Installing and Configuring Webpack

Webpack is a module bundler which takes modules with dependencies and generates static assets by bundling them together based on some configuration.

Let’s start with installing webpack using npm

Webpack requires some configuration settings to carry out its work and the best practice is doing it via a config file called webpack.config.js.

Update the config file as follows

The holds the directory path of the React application's codebase and the represents the directory path of the bundle file output.

As the name suggests, entry specifies the entry file using which the bundling process starts. If you are coming from C# or Java, it’s similar to the class that contains main method. Webpack supports multiple entry points too. Here the index.jsx in the src directory is the starting point of the application

The output instructs Webpack what to do after the bundling process has been completed. Here, we are instructing it to use the build directory to output the bundled file with the name bundle.js

Let’s create the index.jsx file in the ./src and add the following code to verify this configuration.

Now in the terminal run the following command

The above command runs the webpack in the development mode and generates the bundle.js file and its associated map file in the build/ directory.

To make it more interactive, create an index.html file in the src directory and modify it to use this bundle.js file

Now if you open the browser, you can see the Hello World! in the console log.

Setting Up Babel-Loader

As we have seen in the beginning, by using JSX and ES6 we can be more productive while working with React. But the JSX syntax and ES6, are not supported in all the browsers.

Hence, if we are using them in the React code, we need to use a tool which translates them to the format that has been supported by the browsers. It’s where babel comes into the picture.

While installing Webpack, we touched a little on loaders. Webpack uses loaders to translate the file before bundling them

To setup, install the following npm packages

The babel-preset-es2015 and babel-preset-react are plugins being used by the babel-loader to translate ES6 and JSX syntax respectively.

As we did for Webpack, babel-loader also requires some configuration. Here we need to tell it to use the ES6 and JSX plugins.

Create a file and update it as below

The next step is telling Webpack to use the babel-loader while bundling the files

open webpack.config.js file and update it as below

The loaders property takes an array of loaders, here we are just using babel-loader. Each loader property should specify what are the file extension it has to process via the test property. Here we have configured it to process both .js and .jsx files using the regular expression. The include property specifies what is the directory to be used to look for these file extensions. The loader property represents the name of the loader.

Now we are done with all the setup. Let’s write some code in React.

Hello React

Use npm to install react and react-dom

Replace the existing statement in the index.jsx with the following content

Then run the following command to update the bundle file with the new changes

Now, if you open the index.html in the browser, you can see Hello React

Making Webpack Watch Changes

Running the webpack command every time when you change the file is not a productive workflow. We can easily change this behavior by using the following command

Now Webpack is running in the watch mode, which will automatically bundle the file whenever there is a change detected. To test it, change Hello React to something else and refresh the index.html in the browser. You can see your new changes.

If you don’t like refreshing the browser to see the changes, you can use react-hot-loader!

Using npm as a tool runner

The command can be made even simpler by leveraging npm.

Update the as below

Now the command runs Webpack in production mode, which minimizes the bundle file automatically, and the command runs the Webpack in the watch mode.

Running Express Server

Use npm to install express and path

create server.js file in project directory and update it as below