webpack.config.js

const Webpack = require("webpack");
const Glob = require("glob");
const CopyWebpackPlugin = require("copy-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const ManifestPlugin = require("webpack-manifest-plugin");
const CleanObsoleteChunks = require("webpack-clean-obsolete-chunks");
const TerserPlugin = require("terser-webpack-plugin");
const LiveReloadPlugin = require("webpack-livereload-plugin");

const configurator = {
    entries: function () {
        const entries = {
            application: [
                './node_modules/jquery-ujs/src/rails.js',
                './assets/css/application.scss',
            ],
        };

        Glob.sync("./assets/*/*.*").forEach((entry) => {
            if (entry === './assets/css/application.scss') {
                return
            }

            let key = entry.replace(/(\.\/assets\/(src|js|css|go)\/)|\.(ts|js|s[ac]ss|go)/g, '')
            if (key.startsWith("_") || (/(ts|js|s[ac]ss|go)$/i).test(entry) === false) {
                return
            }

            if (entries[key] == null) {
                entries[key] = [entry]
                return
            }

            entries[key].push(entry)
        })
        return entries
    },

    plugins() {
        return [
            new Webpack.ProvidePlugin({$: "jquery", jQuery: "jquery"}),
            new MiniCssExtractPlugin({filename: "[name].[contenthash].css"}),
            new CopyWebpackPlugin([{from: "./assets", to: ""}], {
                copyUnmodified: true,
                ignore: ["css/**", "js/**", "src/**"]
            }),
            new Webpack.LoaderOptionsPlugin({minimize: true, debug: false}),
            new ManifestPlugin({fileName: "manifest.json"}),
            new CleanObsoleteChunks()
        ]
    },

    moduleOptions: function () {
        return {
            rules: [
                {
                    test: /\.s[ac]ss$/,
                    use: [
                        MiniCssExtractPlugin.loader,
                        {loader: "css-loader", options: {sourceMap: true}},
                        {loader: "postcss-loader", options: {sourceMap: true}},
                        {loader: "sass-loader", options: {sourceMap: true}}
                    ]
                },
                {test: /\.tsx?$/, use: "ts-loader", exclude: /node_modules/},
                {test: /\.jsx?$/, loader: "babel-loader", exclude: /node_modules/},
                {test: /\.(woff|woff2|ttf|svg)(\?v=\d+\.\d+\.\d+)?$/, use: "url-loader"},
                {test: /\.eot(\?v=\d+\.\d+\.\d+)?$/, use: "file-loader"},
                {test: require.resolve("jquery"), use: "expose-loader?jQuery!expose-loader?$"},
                {test: /\.go$/, use: "gopherjs-loader"}
            ]
        }
    },

    buildConfig: function () {
        // NOTE: If you are having issues with this not being set "properly", make
        // sure your GO_ENV is set properly as `buffalo build` overrides NODE_ENV
        // with whatever GO_ENV is set to or "development".
        const env = process.env.NODE_ENV || "development";
        console.log(env)

        const config = {
            mode: env,
            entry: configurator.entries(),
            output: {filename: "[name].[hash].js", path: `${__dirname}/public/assets`},
            plugins: configurator.plugins(),
            module: configurator.moduleOptions(),
            resolve: {
                extensions: ['.ts', '.js', '.json']
            }
        };

        if (env === "development") {
            config.plugins.push(new LiveReloadPlugin({appendScriptTag: true}))
            return config
        }

        const terser = new TerserPlugin({
            terserOptions: {
                compress: {},
                mangle: {
                    keep_fnames: true
                },
                output: {
                    comments: false,
                },
            },
            extractComments: false,
        })

        config.optimization = {
            minimizer: [terser]
        }

        return config
    }
}

module.exports = configurator.buildConfig()