Gulpfile for Babel using gulp-watch built for Node.js 4.0

gulpfile-babel.js

var gulp = require('gulp')
var watch = require('gulp-watch')
var babel = require('gulp-babel')
var plumber = require('gulp-plumber')

var libDir = 'lib/'
var srcDir = 'src/**/*.es6'

function runBabel () {
  return gulp.src(srcDir)
    .pipe(plumber(err => console.log(err.stack)))
    .pipe(babel())
    .pipe(plumber.stop())
    .pipe(gulp.dest(libDir))
}

gulp.task('babel', () => runBabel())

gulp.task('babel-watch', ['babel'], cb => {
  watch(srcDir, () =>
    runBabel()
      .pipe(watch(srcDir))
      .on('end', cb)
  )
})