webpack.config.js

const path = require('path')
const webpack = require('webpack')
const FilemanagerPlugin = require('filemanager-webpack-plugin')
const TerserPlugin = require('terser-webpack-plugin')
const CopyWebpackPlugin = require('copy-webpack-plugin')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const { CleanWebpackPlugin } = require('clean-webpack-plugin')
const MiniCssExtractPlugin = require('mini-css-extract-plugin')
const ExtensionReloader = require('webpack-extension-reloader')
const WextManifestWebpackPlugin = require('wext-manifest-webpack-plugin')
const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin')

const nodeEnv = process.env.NODE_ENV || 'development'
const targetBrowser = process.env.TARGET_BROWSER

const extensionReloaderPlugin =
  nodeEnv === 'development'
    ? new ExtensionReloader({
        port: 9090,
        reloadPage: true,
        entries: {
          // TODO: reload manifest on update
          contentScript: 'contentScript',
          background: 'background',
          extensionPage: [
            // 'popup',
            'options'
          ]
        }
      })
    : () => {
        this.apply = () => {}
      }

const getExtensionFileType = (browser) => {
  if (browser === 'opera') {
    return 'crx'
  }
  if (browser === 'firefox') {
    return 'xpi'
  }

  return 'zip'
}

module.exports = {
  devtool: false, // https://github.com/webpack/webpack/issues/1194#issuecomment-560382342

  mode: nodeEnv,

  stats: {
    all: false,
    builtAt: true,
    errors: true,
    hash: true
  },

  entry: {
    manifest: './source/manifest.json',
    background: './source/scripts/background.js',
    contentScript: './source/scripts/contentScript.js',
    inject: './source/styles/inject.scss',
    options: './source/scripts/options.js'
  },

  output: {
    path: path.resolve(__dirname, 'extension', targetBrowser),
    filename: 'js/[name].bundle.js'
  },

  module: {
    rules: [
      {
        type: 'javascript/auto', // prevent webpack handling json with its own loaders,
        test: /manifest\.json$/,
        use: {
          loader: 'wext-manifest-loader',
          options: {
            usePackageJSONVersion: true // set to false to not use package.json version for manifest
          }
        }
      },
      {
        test: /.(js|jsx)$/,
        include: [path.resolve(__dirname, 'source/scripts')],
        loader: 'babel-loader',

        options: {
          plugins: ['syntax-dynamic-import'],

          presets: [
            [
              '@babel/preset-env',
              {
                modules: false
              }
            ]
          ]
        }
      },
      {
        test: /\.scss$/,
        use: [
          {
            loader: MiniCssExtractPlugin.loader // It creates a CSS file per JS file which contains CSS
          },
          {
            loader: 'css-loader',
            options: {
              sourceMap: nodeEnv === 'development'
            }
          },
          {
            loader: 'postcss-loader',
            options: {
              postcssOptions: {
                plugins: [
                  [
                    'autoprefixer',
                    {
                      // Options
                    }
                  ]
                ]
              }
            }
          },
          'resolve-url-loader',
          'sass-loader'
        ]
      }
    ]
  },

  plugins: [
    new webpack.ProgressPlugin(),
    // Generate manifest.json
    new WextManifestWebpackPlugin(),
    // Generate sourcemaps
    new webpack.SourceMapDevToolPlugin({ filename: false }),
    new webpack.EnvironmentPlugin(['NODE_ENV', 'TARGET_BROWSER']),
    new CleanWebpackPlugin({
      cleanOnceBeforeBuildPatterns: [
        path.join(process.cwd(), `extension/${targetBrowser}`),
        path.join(
          process.cwd(),
          `extension/${targetBrowser}.${getExtensionFileType(targetBrowser)}`
        )
      ],
      cleanStaleWebpackAssets: false,
      verbose: true
    }),
    // write css file(s) to build folder
    new MiniCssExtractPlugin({ filename: 'css/[name].css' }),
    new HtmlWebpackPlugin({
      template: 'source/options.html',
      inject: 'body',
      hash: true,
      chunks: ['options'],
      filename: 'options.html'
    }),
    // new HtmlWebpackPlugin({
    //   template: 'source/popup.html',
    //   inject: 'body',
    //   hash: true,
    //   chunks: ['popup'],
    //   filename: 'popup.html'
    // }),
    // copy static assets
    new CopyWebpackPlugin({
      patterns: [{ from: 'source/assets', to: 'assets' }]
    }),
    // plugin to enable browser reloading in development mode
    extensionReloaderPlugin
  ],

  optimization: {
    minimize: nodeEnv !== 'development',
    minimizer: [
      new TerserPlugin({
        parallel: true,
        terserOptions: {
          format: {
            comments: false
          }
        },
        extractComments: false
      }),
      new OptimizeCSSAssetsPlugin({
        cssProcessorPluginOptions: {
          preset: ['default', { discardComments: { removeAll: true } }]
        }
      }),
      new FilemanagerPlugin({
        events: {
          onEnd: {
            archive: [
              {
                format: 'zip',
                source: path.join(__dirname, 'extension', targetBrowser),
                destination: `${path.join(__dirname, 'extension', targetBrowser)}.${getExtensionFileType(targetBrowser)}`,
                options: { zlib: { level: 6 } }
              }
            ]
          }
        }
      })
    ]
  }
}