webpack.config.js

const path = require('path');
const packagejson = require('./package.json');

const dashLibraryName = packagejson.name.replace(/-/g, '_');

module.exports = (env, argv) => {
    let mode;

    const overrides = module.exports || {};

    // if user specified mode flag take that value
    if (argv && argv.mode) {
        mode = argv.mode;
    }

    // else if configuration object is already set (module.exports) use that value
    else if (overrides.mode) {
        mode = overrides.mode;
    }

    // else take webpack default (production)
    else {
        mode = 'production';
    }

    let filename = (overrides.output || {}).filename;
    if (!filename) {
        const modeSuffix = mode === 'development' ? 'dev' : 'min';
        filename = `${dashLibraryName}.${modeSuffix}.js`;
    }

    const entry = overrides.entry || {main: './src/lib/index.js'};

    const devtool =
        overrides.devtool ||
        (mode === 'development' ? 'eval-source-map' : undefined);

    const externals =
        'externals' in overrides
            ? overrides.externals
            : {
                  react: 'React',
                  'react-dom': 'ReactDOM',
                  'plotly.js': 'Plotly',
              };

    return {
        mode,
        entry,
        output: {
            path: path.resolve(__dirname, dashLibraryName),
            filename,
            library: dashLibraryName,
            libraryTarget: 'window',
        },
        externals,
        module: {
            rules: [
                {
                    test: /\.js$/,
                    exclude: /node_modules/,
                    use: {
                        loader: 'babel-loader',
                    },
                },
                {
                    test: /\.css$/,
                    use: [
                        {
                            loader: 'style-loader',
                        },
                        {
                            loader: 'css-loader',
                        },
                    ],
                },
            ],
        },
        devtool,
    };
};