with-web-worker.js

const defaultPluginOptions = {
  extension: /\.worker.js$/,
};

const plugin = (config, pluginOptions, nextOptions) => {
  const { extension } = pluginOptions;

  config.module.rules.push({
    test: extension,
    use: [
      nextOptions.defaultLoaders.babel,
      {
        loader: 'worker-loader',
        options: {
          fallback: true,
          inline: false,
        },
      },
    ],
  });

  return config;
};

module.exports = (pluginOptions = defaultPluginOptions) => (
  nextConfig = {}
) => {
  return Object.assign({}, nextConfig, {
    webpack(config, nextOptions) {
      if (!nextOptions.defaultLoaders) {
        throw new Error(
          'This plugin is not compatible with Next.js versions below 5.0.0 https://err.sh/next-plugins/upgrade'
        );
      }

      config = plugin(config, pluginOptions, nextOptions);

      if (typeof nextConfig.webpack === 'function') {
        return nextConfig.webpack(config, nextOptions);
      }
      return config;
    },
  });
};