frontEndStore.js

import {
  LoginReducer,
  CartsReducer
} from 'shared-state/lib/Reducers';

import { appSpecificReducer } from './localReducer'

const rootReducer = combineReducers({
  appSpecificReducer,
  LoginReducer,
  CartsReducer
});

const store = createStore(
  rootReducer,
  composeEnhancers(applyMiddleware(reduxThunk, reduxStoreEvents))
);

export default store;

index.js

export { default as CartsReducer } from './Cart/reducer.js';
export { default as LoginReducer } from './Login/reducer.js';

webpack.config.js

const path = require('path');
const fs = require('fs');
const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;
const TerserPlugin = require('terser-webpack-plugin');

const entry = {
  Reducers: ['./modules']
};

fs.readdirSync('./modules').forEach((folder) => {
  if (folder.toString() !== 'index.js') {
    fs.readdirSync(`./modules/${folder}`).forEach((file) => {
      const fileToString = file.toString().split('.');
      if (fileToString.includes('actions') && !file.includes('test.js')) {
        entry[`${fileToString[0]}Actions`] = [`./modules/${folder}/${file}`];
      }
    });
  }
});

const plugins = [];

const externals = {
  redux: 'redux',
  lodash: 'lodash',
};

if (process.env.PROFILER === '1') {
  plugins.push(new BundleAnalyzerPlugin());
}

module.exports = {
  module: {
    rules: [
      {
        test: /\.m?js$/,
        exclude: /(node_modules)/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env']
          }
        }
      }
    ]
  },
  optimization: {
    minimizer: [
      new TerserPlugin({
        terserOptions: {
          keep_fnames: true
        }
      })
    ]
  },
  context: __dirname,
  entry,
  mode: process.env.NODE_ENV === 'production' ? 'production' : 'development',
  plugins,
  output: {
    path: path.join(__dirname, 'lib'),
    chunkFilename: '[name].[chunkhash].js',
    filename: '[name].js',
    libraryTarget: 'umd',
    library: 'shared-state'
  },
  externals
};