How to bundle JS and CSS file independently with Webpack?

Question

I have a few JS and SCSS files. I need Webpack 4 to bundle each JS entry to one JS file and each SCSS entry to one CSS file. The JS files don't import the SCSS files. I try to do it with the following webpack.config.js :

const path = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
  entry: {
    scriptFoo: './src/js/scriptFoo.js',
    scriptBar: './src/js/scriptBar.js',
    // ...
    styleBaz: './src/css/styleBaz.scss',
    styleBaq: './src/css/styleBaq.scss'
    // ...
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: 'babel-loader'
      },
      {
        test: /\.(scss|sass)$/,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader',
          'postcss-loader',
          'sass-loader'
        ]
      }
    ]
  },
  output: {
    filename: '[name].js',
    path: path.resolve(__dirname, 'dist')
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: '[name].css'
    })
  ]
};

It works fine, Webpack puts the compiled files to the dist directory. But it also creates an excess dummy JS file for each SCSS file in the dist directory:

webpack.config.js
src/
  js/
    scriptFoo.js
    scriptBar.js
    ...
  css/
    styleBaz.scss
    styleBaq.scss
    ...
dist/
  scriptFoo.js
  scriptBar.js
  ...
  styleBaz.css
  styleBaz.js // Excess
  styleBaq.css
  styleBaq.js // Excess
  ...

How to make Webpack not to create the excess JS files?

Answer 1

It is because for each property in the entry object ,The js file is created in output destinations.

output: { filename: '[name].js', path: path.resolve(__dirname, 'dist') },

Webpack creating dummy js when css is an entry point is a known bug, which has not been fixed yet.

Also having multiple entry files in the entry configuration will also affect treeshaking capabilties

Answer 2

Use the ignore-emit-webpack-plugin Webpack plugin to not create the excess file. First install it by running in a console:

npm install --save-dev ignore-emit-webpack-plugin

Then add it to your Webpack configuration:

const IgnoreEmitPlugin = require('ignore-emit-webpack-plugin');

module.exports = {
  // ...
  plugins: [
    // ...
    new IgnoreEmitPlugin(['styleBaz.js', 'styleBaq.js']) // Or simply: new IgnoreEmitPlugin(/^style.*\.js$/)
  ]
};