gulpfile.js

var gulp = require('gulp')
var eslint = require('gulp-eslint')
var source = require('vinyl-source-stream')
var connect = require('gulp-connect')
var babelify = require('babelify')
var browserify = require('browserify')
var es = require('event-stream')

var config = {
  src: {
    dir: 'src/javascripts',
    mainjs: 'attache.js'
  },
  dest: {
    dir: 'app/assets/javascripts'
  }
}

gulp.task('lint', function () {
  return gulp.src([config.src.dir + '/**/*.js', 'gulpfile.js'])
    .pipe(eslint())
    .pipe(eslint.format())
    .pipe(eslint.failAfterError())
})

gulp.task('watch', function () {
  gulp.watch([config.src.dir + '/**/*.js', 'gulpfile.js'], ['js'])
  gulp.watch(['app/index.html'], connect.reload())
})

gulp.task('js', ['lint'], function (done) {
  var files = [
    config.src.dir + '/' + 'attache/cors_upload.js',
    config.src.dir + '/' + 'attache/bootstrap3.js',
    config.src.dir + '/' + 'attache/file_input.js',
    config.src.dir + '/' + config.src.mainjs
  ]

  var tasks = files.map(function (entry) {
    var name = entry.substring(config.src.dir.length + 1)
    return browserify({ entries: [entry], standalone: name.replace(/\.\w+$/, '').replace(/\W+/g, '_') })
      .transform(babelify)
      .bundle()
      .on('error', function () {
        console.error.apply(console, arguments)
        done()
      })
      .pipe(source(name))
      .pipe(gulp.dest(config.dest.dir))
      .pipe(connect.reload())
  })
  // create a merged stream
  return es.merge.apply(null, tasks)
})

gulp.task('connect', ['js', 'watch'], function () {
  connect.server({
    root: ['app'],
    port: 9005,
    base: 'http://localhost',
    livereload: true
  })
})

gulp.task('default', ['js', 'watch'])