gulpfile.js

var gulp = require('gulp');
var source = require('vinyl-source-stream'); // Used to stream bundle for further handling
var browserify = require('browserify');
var watchify = require('watchify');
var reactify = require('reactify'); 
var autoprefixer = require('gulp-autoprefixer');
var sourcemaps = require('gulp-sourcemaps');
var gutil = require('gulp-util');
var add = require('gulp-add-src');

var uglify = require('gulp-uglify');
var streamify = require('gulp-streamify');
var htmlreplace = require('gulp-html-replace');

var path = {
  IMG: 'src/images',
  CSS: 'src/css/app.css',
  HTML: 'src/index.html',
  MINIFIED_OUT: 'react-slider.min.js',
  OUT: 'react-slider.js',
  DEST: 'dist',
  DEST_BUILD: 'dist/build',
  DEST_SRC: 'dist/src',
  ENTRY_POINT: './src/js/app.js'
};

gulp.task('copy', function(){
  gulp.src(path.HTML)
    .pipe(gulp.dest(path.DEST));
  gulp.src(path.CSS)
    .pipe(gulp.dest(path.DEST+"/css/"));
});

gulp.task('watch', function() {
  gulp.watch([path.CSS,path.HTML], ['copy']);

  var watcher  = watchify(browserify({
    entries: [path.ENTRY_POINT],
    transform: [reactify],
    debug: true,
    cache: {}, packageCache: {}, fullPaths: true
  }));

  return watcher.on('update', function () {
    watcher.bundle()
      .pipe(source(path.OUT))
      .pipe(gulp.dest(path.DEST_SRC))
      console.log('Updated');
  })
    .bundle()
    .pipe(source(path.OUT))
    .pipe(gulp.dest(path.DEST_SRC));
});

gulp.task('build', function(){
  browserify({
    entries: [path.ENTRY_POINT],
    transform: [reactify],
  })
    .bundle()
    .pipe(source(path.MINIFIED_OUT))
    .pipe(streamify(uglify()))
    .pipe(gulp.dest(path.DEST_BUILD));
});

gulp.task('replaceHTML', function(){
  gulp.src(path.HTML)
    .pipe(htmlreplace({
      'js': 'build/' + path.MINIFIED_OUT
    }))
    .pipe(gulp.dest(path.DEST));
});

gulp.task('production', ['replaceHTML', 'build']);
gulp.task('default', ['watch']);