gulpfile.js

/*!
 * gulp
 * $ npm install gulp-ruby-sass gulp-autoprefixer gulp-minify-css gulp-jshint gulp-concat gulp-uglify gulp-imagemin gulp-clean gulp-notify gulp-rename gulp-livereload gulp-cache --save-dev
 *
 * much helpful
 * @see http://markgoodyear.com/2014/01/getting-started-with-gulp/
 * @see http://mattbanks.me/gulp-wordpress-development/
 */

// Load plugins
var gulp = require('gulp'),
    sass = require('gulp-ruby-sass'),
    autoprefixer = require('gulp-autoprefixer'),
    minifycss = require('gulp-minify-css'),
    jshint = require('gulp-jshint'),
    uglify = require('gulp-uglify'),
    imagemin = require('gulp-imagemin'),
    rename = require('gulp-rename'),
    clean = require('gulp-clean'),
    concat = require('gulp-concat'),
    notify = require('gulp-notify'),
    cache = require('gulp-cache'),
    livereload = require('gulp-livereload');

// Styles
gulp.task('styles', function() {
  return gulp.src('assets/css/source/*.scss')
    .pipe(sass({ style: 'expanded', compass: true }))
    .pipe(autoprefixer('last 2 version', 'safari 5', 'ie 8', 'ie 9', 'opera 12.1', 'ios 6', 'android 4'))
    .pipe(gulp.dest('assets/css/build'))
    .pipe(rename({ suffix: '.min' }))
    .pipe(minifycss())
    .pipe(gulp.dest('assets/css'))
    .pipe(notify({ message: 'Styles task complete' }));
});

// Scripts
gulp.task('scripts', function() {
  return gulp.src('assets/js/source/*.js')
    .pipe(jshint('.jshintrc'))
    .pipe(jshint.reporter('default'))
    .pipe(concat('main.js'))
    .pipe(gulp.dest('assets/js/build'))
    .pipe(rename({ suffix: '.min' }))
    .pipe(uglify())
    .pipe(gulp.dest('assets/js'))
    .pipe(notify({ message: 'Scripts task complete' }));
});

// Images
gulp.task('images', function() {
  return gulp.src('assets/img/**/*')
    .pipe(cache(imagemin({ optimizationLevel: 3, progressive: true, interlaced: true })))
    .pipe(gulp.dest('assets/img'))
    .pipe(notify({ message: 'Images task complete' }));
});

// Clean
gulp.task('clean', function() {
  return gulp.src(['assets/css', 'assets/js', 'assets/img'], {read: false})
    .pipe(clean());
});

// Default task
gulp.task('default', ['clean'], function() {
    gulp.start('css', 'js', 'img');
});

// Watch
gulp.task('watch', function() {

  // Watch .scss files
  gulp.watch('assets/css/*.scss', ['styles']);

  // Watch .js files
  gulp.watch('assets/js/*.js', ['scripts']);

  // Watch image files
  gulp.watch('assets/img/*', ['images']);

  // Create LiveReload server
  var server = livereload();

  // Watch any files in assets/, reload on change
  gulp.watch(['assets/**']).on('change', function(file) {
    server.changed(file.path);
  });

});