gulpfile.js

var gulp         = require('gulp'),
    prettify     = require('gulp-jsbeautifier'),
    runSequence = require('run-sequence'),
    gutil       = require('gulp-util'),
    babel       = require('gulp-babel');

var paths = {
  scripts: [
    'assets/js/*.js',
    'server.js',
    'controllers/*.js',
    'utils/*.js'
  ]
}

gulp.task('verify-js', function() {
  gulp.src(['assets/js/*.js'])
    .pipe(prettify({
      config: '.jsbeautifyrc',
      mode: 'VERIFY_ONLY'
    }));
});

gulp.task('prettify-js', function() {
  gulp.src(paths.scripts)
    .pipe(prettify({
      config: '.jsbeautifyrc',
      mode: 'VERIFY_AND_WRITE'
    }))
    .pipe(gulp.dest(function(file) {
      return file.base;
    }));
});

gulp.task('prettify-html', function() {
  gulp.src(['assets/**/*.html'])
    .pipe(prettify({
      braceStyle: "collapse",
      indentChar: " ",
      indentSize: 4
    }))
    .pipe(gulp.dest('assets/'));
});

gulp.task('prettify-code', function() {
  runSequence(
    ['prettify-js', 'prettify-html']
  );
});

gulp.task('transpilation', function() {
  gulp.src(['controllers/*.js'])
    .pipe(babel({highlightCode: false}))
    .pipe(gulp.dest('build'))
    .on('error', gutil.log);
});

gulp.task('default', function() {
  runSequence(
    ['prettify-code', 'transpilation']
  );
});