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Getting started with basic webpack setup

I hope I don't need to introduce you to Webpack. By this time, you would have read through the webpack documentation and figured out that the page is for the NASA people. However, I would like to start with this Gem:

So, here's a very, very basic setup of Webpack to help you get started. I will keep this article as simple as I can. Also I assume that you know the basics of NPM and have installed Node in your machine.

0. Our Goal

We are going to create a simple setup that will have the following structure:

app
|--src
|   |--js
|   |   `--main.js
|   `--scss
|       `--main.scss
|--resources
|   `--js
|       `--bundle.js
|--package.json
`--index.html

Go ahead and create those files in your favorite editor (except the bundle.js). We will have the webpack to:

  1. bundle our JavaScript files from src folder and generate the output to resources/js/bundle.js file.
  2. Compile .scss file to .css file and bundle it with our JS file.
  3. Have a auto reloading mechanism that auto refresh the browser as you make changes to your JavaScript / Sass files.

1. Installing Webpack and bundling JavaScript

First, lets add some test code to the src\js\main.js file.

console.log('Hello Webpack');

You need to run npm install webpack -g (to have the webpack command available globally). Also, it is better to install it as a dev dependency too. So run npm install webpack --save-dev.

Now that you have webpack installed, it's time to tell it what to do. We do this via a configuration file. Create a file called webpack.config.js in the root folder and add the following content in it.

/* webpack.config.js */
module.exports = {
    entry: './src/js/main.js',
    output: {
        path: './resources/js',
        filename: 'bundle.js',
        publicPath: '/resources/js'
    }
}

The configuration tells webpack:

  1. What is our starting point: entry
  2. Where to generate the bundled file: output.path / output.filename
  3. What's the path that browsers will ues to load the bundled file: output.publicPath. This is important to have the auto reload work properly when we use webpack-dev-server.

Now if you run webpack in your command line, you will see that the JavaScript file is getting bundled and the output is generated in resources/js/bundle.js file.

2. Compiling SASS files

Let's setup SASS compilation. In your src\sass\main.scss add some test SASS code.

body {
    background-color: #f00;
}

To enable SASS compilation, we need to install loaders which will be used by webpack. Run npm install style-loader css-loader sass-loader --save-dev.

Next, you need to update webpack.config.js file, instructing webpack to use the loaders. The final content of webpack configuration will be:

module.exports = {
    entry: './src/js/main.js',
    output: {
        path: './resources/js',
        filename: 'bundle.js',
        publicPath: '/resources/js'
    },
    module: {
        loaders: [
            {
                test: /\.scss$/,
                loaders: ['style', 'css', 'sass']
            }
        ]
    }
}

Take a look at the module.loaders configuration. We are adding a new loader that tests for the .scss extension and for the matching files, uses a series of transformation (from right to left) sass -> css -> style.

Now update src\js\main.js to include the SASS file.

require('../scss/main.scss');
console.log('Hello Webpack');

Now if you run webpack, you will see that the SASS file is converted and bundled together with our JS files into resources/js/bundle.js.

3. Serving and Auto reloading changes.

We need a web server that serves our file. Webpack provides one. Install it with npm install webpack-dev-server -g (to have the command available globally) and npm install webpack-dev-server --save-dev to define a dev dependency in your package.json.

Add below content to the index.html file to load our bundled file (omitting boilerplate code for brevity)

<html>
    <body>
        <h1>Hello World</h1>
        <script type="text/javascript" src="resources/js/bundle.js"></script>
    </body>
</html>

Now run webpackdev-server --inline. The parameter --inline instruct the webpack server to auto reload changes. Without it, it will just serve the files.

Now open this url in a browser: http://localhost:8080/ and you will see the text Hello World in a red color background. Now update any of the main.scss or main.js and you will see the changes are reflected immediately.

Happy Webpacking!

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