.babelrc

{
  "presets": ["es2015", "stage-0", "react"],
  "env": {
    "development": {
      "plugins": [
        ["react-transform", {
          "transforms": [
            {
              "transform": "react-transform-hmr",
              "imports": ["react"],
              "locals": ["module"]
            },
            {
              "transform": "react-transform-catch-errors",
              "imports": ["react", "redbox-react"]
            }
          ]
        }]
      ]
    }
  }
}

output-browser.js

[HMR] Attempting websocket connection to http://localhost:3123
[HMR] Websocket connection successful.
[HMR] Updated modules ["client/wireframes/pages/home.js", "client/wireframes/routes.js", "client/app.js"]

output-console.txt

[14:01:31] Starting 'watch'...
[14:01:31] Starting 'build'...
[14:01:31] Starting 'css'...
[14:01:31] Finished 'css' after 51 ms
[14:01:31] Starting 'build-src'...
[14:01:32] Finished 'build-src' after 797 ms
[14:01:32] Starting 'build-libs'...
[14:01:34] Finished 'build-libs' after 2.56 s
[14:01:34] Starting 'copy-html'...
[14:01:34] Finished 'copy-html' after 2.81 ms
[14:01:34] Finished 'build' after 3.42 s
[14:01:34] Starting 'watchClient'...
[14:01:34] Finished 'watchClient' after 11 ms
[14:01:34] Starting 'watchExternalLibraries'...
[14:01:34] Finished 'watchExternalLibraries' after 2.21 ms
[14:01:34] Starting 'watchPackageJSON'...
[14:01:34] Finished 'watchPackageJSON' after 738 μs
[14:01:34] Starting 'watchBrowserify'...
[14:01:34] Finished 'watchBrowserify' after 53 ms
[14:01:34] Finished 'watch' after 3.49 s
14:01:37 GMT+0100 (CET) [HMR] Emitting updates
14:01:37 GMT+0100 (CET) [HMR] Listening on localhost:3123
[14:01:38] browserify 1901419 bytes written (3.63 seconds)
14:01:40 GMT+0100 (CET) [HMR] User connected, syncing
14:01:44 GMT+0100 (CET) [HMR] User connected, syncing
14:01:50 GMT+0100 (CET) [HMR] Emitting updates
[14:01:50] browserify 1901416 bytes written (0.43 seconds)

tasks-watchBrowserify.js

'use strict';

module.exports = (gulp, config) => {
  return {
    watchBrowserify: {
      fn: watchBrowserify,
      help: 'Watches the browserify build.'
    }
  };

  function watchBrowserify() {
    const babelify = require('babelify');
    const browserify = require('browserify');
    const browserifyHMR = require('browserify-hmr');
    const uglifyify = require('uglifyify');
    const vinylSourceStream = require('vinyl-source-stream');
    const watchify = require('watchify');
    const gutil = require('gulp-util');

    const commonBrowserify = require('./common/browserify');

    const browserifyBundle = browserify('client/app.js', {
      cache: {},
      packageCache: {},
      debug: false,
    });

    // Transforms
    browserifyBundle.transform(babelify);
    browserifyBundle.transform(commonBrowserify.getImportFilter(browserifyBundle));

    if (config.uglify) {
      browserifyBundle.transform(config.uglify, uglifyify);
    }

    // Plugins
    browserifyBundle.plugin(browserifyHMR);
    browserifyBundle.plugin(watchify);

    commonBrowserify.getExternalLibsSync();

    function bundle() {
      browserifyBundle.bundle()
        .pipe(vinylSourceStream('main.js'))
        .pipe(gulp.dest(config.folders.build))
        .on('end', error => {
          if (error) {
            console.error(error);
          }

          commonBrowserify.setExternalLibsSync();
        });
    }

    browserifyBundle
      .on('log', (message) => {
        gutil.log('browserify', message);
      });

    browserifyBundle
      .on('update', bundle);

    bundle();
  }
};