gulpfile.js

var gulp        = require('gulp');
var sequence    = require('run-sequence');
var sourcemaps  = require('gulp-sourcemaps');
var plumber     = require('gulp-plumber')

var stylus      = require('gulp-stylus');
var nib         = require('nib');
var jeet        = require('jeet');

var browserify  = require('browserify');
var watchify    = require('watchify');
var gutil       = require('gulp-util');
var source      = require('vinyl-source-stream');
var babelify    = require('babelify');

var del         = require('del');

var browserSync = require('browser-sync');

//**************************************************************************************************
// Top-level tasks
//**************************************************************************************************

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

gulp.task('serve', ['build', 'bundle:watch'], function() {
  browserSync({server: 'build'});

  gulp.watch('src/pages/**.html',    ['pages']);
  gulp.watch('src/styles/**/*.styl', ['styles']);
  gulp.watch('src/images/**/*',      ['assets']);
});

gulp.task('build', function() {
  return sequence('clean', ['styles', 'bundle', 'pages', 'assets']);
});

//**************************************************************************************************
// Sub-tasks
//**************************************************************************************************

gulp.task('clean', function(cb) {
  return del(['build'], cb);
});

gulp.task('styles', function() {
  return gulp.src('src/styles/main.styl')
    .pipe(plumber())
    .pipe(sourcemaps.init())
    .pipe(stylus({use: [nib(), jeet()]}))
    .pipe(sourcemaps.write())
    .pipe(gulp.dest('build/styles'))
    .pipe(browserSync.stream());
});

gulp.task('assets', function() {
  return gulp.src('src/images/**/*')
    .pipe(gulp.dest('build/images'))
    .pipe(browserSync.stream());
});

gulp.task('pages', function() {
  return gulp.src('src/pages/**/*')
    .pipe(plumber())
    .pipe(gulp.dest('build'))
    .pipe(browserSync.stream());
});

gulp.task('bundle', function() { return bundle() });
gulp.task('bundle:watch', function() { return bundle({watch: true}); });

var bundler = browserify('src/scripts/site.js', watchify.args);
bundler.transform(babelify);

function bundle(opts) {
  if(opts && 'watch' in opts && opts.watch) {
    bundler = watchify(bundler);
    bundler.on('update', bundle);
  }

  return bundler.bundle()
    .on('error', function(error) {
      gutil.log(error.toString());
      this.emit('end');
      browserSync.notify('Browserify error');
    })
    .pipe(plumber())
    .pipe(source('bundle.js'))
    .pipe(gulp.dest('build/scripts'))
    .pipe(browserSync.stream());
}