gulpfile.js

var gulp = require('gulp');
var webpack = require('webpack');
var path = require('path');
var fs = require('fs');
var DeepMerge = require('deep-merge');
var nodemon = require('nodemon');

var deepmerge = DeepMerge(function(target, source, key) {
  if(target instanceof Array) {
    return [].concat(target, source);
  }
  return source;
});

// generic
var defaultConfig = {};
if(process.env.NODE_ENV !== 'production') {
  defaultConfig.debug = true;
}

function config(overrides) {
  return deepmerge(defaultConfig, overrides || {});
}

// frontend
var frontendConfig = config({
  entry: {
    index : __dirname + '/public/js/index.js',
    maps : __dirname + '/public/js/maps.js',
    aggregation : __dirname + '/public/js/aggregation.js',
    bootstrap : __dirname + '/public/js/bootstrapStatic.js'
  },
  output: {
    path: path.join(__dirname, './public/dist/js'),
    filename: '[name].js'
  },
  module: {
    loaders: [
      {
        test: /\.jsx?$/,
        loader: 'babel-loader',
        exclude: /node_modules/,
        query: {
          presets: ['es2015', 'react']
        },
      },
      { test: /\.css$/, loader: "style-loader!css-loader" },
      { test: /\.png$/, loader: "url-loader", query: { mimetype: "image/png" }}
    ]
  },
});

//backend

var nodeModules = {};
fs.readdirSync('node_modules')
  .filter(function(x) {
    return ['.bin'].indexOf(x) === -1;
  })
  .forEach(function(mod) {
    nodeModules[mod] = 'commonjs ' + mod;
  });

var backendConfig = config({
    entry: './routes/index.js',
  output: {
    path: path.join(__dirname, './public/dist/js'),
    filename: '[name].js'
  },
  node: {
    __dirname: true,
    __filename: true
   },
   externals: nodeModules,
   plugins: [
     new webpack.IgnorePlugin(/\.(css|less)$/),
    new webpack.BannerPlugin('require("source-map-support").install();',
        { raw: true, entryOnly: false })
   ]
});

// tasks

function onBuild(done) {
  return function(err, stats) {
    if(err) {
      console.log('Error', err);
    }

    if(done) {
      done();
    }
  }
}

gulp.task('frontend-build', function(done) {
  webpack(frontendConfig).run(onBuild(done));
});

gulp.task('frontend-watch', function() {
  webpack(frontendConfig).watch(100, onBuild());
});

gulp.task('backend-build', function(done) {
   webpack(backendConfig).run(onBuild(done));
});

gulp.task('backend-watch', function() {
  webpack(backendConfig).watch(100, function(err, stats) {
    onBuild()(err, stats);
    nodemon.restart();
  });
});

gulp.task('build', ['frontend-build', 'backend-build']);
gulp.task('watch', ['run']);

gulp.task('run', ['frontend-watch', 'backend-watch'], function() {
  nodemon({
    execMap: {
      js: 'node'
    },
    script: 'app.js',
    ignore: ['*'],
    watch: ['public/dist/js/'],
    ext: 'noop'
  }).on('restart', function() {
    console.log('Server started. Listening @ http://localhost:3000');
  });
});