webpack.config.js

const path = require('path');
const { merge } = require('webpack-merge');

const TerserPlugin = require('terser-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const HTMLWebpackPlugin = require('html-webpack-plugin');
const { CleanWebpackPlugin } = require('clean-webpack-plugin');

// Production CSS assets - separate, minimised file
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');

var MODE = process.env.npm_lifecycle_event === 'prod' ? 'production' : 'development';
var withDebug = !process.env['npm_config_nodebug'] && MODE === 'development';
// this may help for Yarn users
// var withDebug = !npmParams.includes("--nodebug");
console.log('\x1b[36m%s\x1b[0m', `** elm-webpack-starter: mode "${MODE}", withDebug: ${withDebug}\n`);

var common = {
    mode: MODE,
    entry: './src/index.js',
    output: {
        path: path.join(__dirname, 'dist'),
        publicPath: '/',
        // FIXME webpack -p automatically adds hash when building for production
        filename: MODE === 'production' ? '[name]-[hash].js' : 'index.js',
    },
    plugins: [
        new HTMLWebpackPlugin({
            // Use this template to get basic responsive meta tags
            template: 'index.html',
            // inject details of output file at end of body
            inject: 'body',
        }),
        new CopyWebpackPlugin({
            patterns: [
                {
                    from: './images/*.*',
                },
                {
                    from: 'favicon.ico',
                },
                {
                    from: './env/*.*',
                },
            ],
        }),
    ],
    resolve: {
        modules: [path.join(__dirname, 'src'), 'node_modules'],
        extensions: ['.js', '.elm', '.scss', '.png'],
    },
    module: {
        rules: [
            {
                test: /\.js$/,
                enforce: 'pre',
                use: ['source-map-loader'],
            },
            {
                test: /\.js$/,
                exclude: /node_modules/,
                use: {
                    loader: 'babel-loader',
                },
            },
            {
                test: /\.scss$/,
                exclude: [/elm-stuff/],
                // see https://github.com/webpack-contrib/css-loader#url
                use: ['style-loader', 'css-loader?url=false', 'sass-loader'],
            },
            {
                test: /\.css$/,
                exclude: [/elm-stuff/],
                use: ['style-loader', 'css-loader?url=false'],
            },
            {
                test: /\.woff(2)?(\?v=[0-9]\.[0-9]\.[0-9])?$/,
                exclude: [/elm-stuff/, /node_modules/],
                use: {
                    loader: 'url-loader',
                    options: {
                        limit: 10000,
                        mimetype: 'application/font-woff',
                    },
                },
            },
            {
                test: /\.(ttf|eot|svg)(\?v=[0-9]\.[0-9]\.[0-9])?$/,
                exclude: [/elm-stuff/, /node_modules/],
                loader: 'file-loader',
            },
            {
                test: /\.(jpe?g|png|gif|svg)$/i,
                exclude: [/elm-stuff/, /node_modules/],
                loader: 'file-loader',
            },
        ],
    },
};

if (MODE === 'development') {
    module.exports = merge(common, {
        optimization: {
            // Prevents compilation errors causing the hot loader to lose state
            noEmitOnErrors: true,
        },
        module: {
            rules: [
                {
                    test: /\.elm$/,
                    exclude: [/elm-stuff/, /node_modules/],
                    use: [
                        { loader: 'elm-hot-webpack-loader' },
                        {
                            loader: 'elm-webpack-loader',
                            options: {
                                // add Elm's debug overlay to output
                                debug: withDebug,
                                //
                                // forceWatch: true,
                            },
                        },
                    ],
                },
            ],
        },
        devServer: {
            inline: true,
            stats: 'errors-only',
            contentBase: path.join(__dirname, 'public'),
            historyApiFallback: true,
            // feel free to delete this section if you don't need anything like this
            before(app) {
                // on port 3000
                app.get('/test', function (req, res) {
                    res.json({ result: 'OK' });
                });
            },
        },
    });
}

if (MODE === 'production') {
    module.exports = merge(common, {
        optimization: {
            minimize: true,
            minimizer: [
                new TerserPlugin({
                    parallel: true,
                    terserOptions: {
                        // https://github.com/webpack-contrib/terser-webpack-plugin#terseroptions
                    },
                }),
                new OptimizeCSSAssetsPlugin({}),
            ],
        },
        plugins: [
            // Delete everything from output-path (/dist) and report to user
            new CleanWebpackPlugin({
                root: __dirname,
                exclude: [],
                verbose: true,
                dry: false,
            }),
            new MiniCssExtractPlugin({
                // Options similar to the same options in webpackOptions.output
                // both options are optional
                filename: '[name]-[hash].css',
            }),
        ],
        module: {
            rules: [
                {
                    test: /\.elm$/,
                    exclude: [/elm-stuff/, /node_modules/],
                    use: {
                        loader: 'elm-webpack-loader',
                        options: {
                            optimize: true,
                        },
                    },
                },
            ],
        },
    });
}