gulpfile.js

'use strict';

// Include Gulp & Tools We'll Use
var gulp = require('gulp');
var $ = require('gulp-load-plugins')();
var del = require('del');
var runSequence = require('run-sequence');
var pagespeed = require('psi');

var AUTOPREFIXER_BROWSERS = [
  'ie >= 10',
  'ie_mob >= 10',
  'ff >= 30',
  'chrome >= 34',
  'safari >= 7',
  'opera >= 23',
  'ios >= 7',
  'android >= 4.4',
  'bb >= 10'
];

// Lint JavaScript
gulp.task('jshint', function () {
  return gulp.src('site-assets/*.js')
    .pipe($.jshint())
    .pipe($.jshint.reporter('jshint-stylish'));
});

// Optimize Images
gulp.task('images', function () {
  return gulp.src('site-assets/*.{png,jpg,svg}')
    .pipe($.cache($.imagemin({
      progressive: true,
      interlaced: true
    })))
    .pipe(gulp.dest('dist/site-assets'))
    .pipe($.size({title: 'images'}));
});

// Copy All Files At The Root Level (app)
gulp.task('copy', function () {
  return gulp.src([
    'architecture-examples/**',
    'dependency-examples/**',
    'vanilla-examples/**',
    'labs/**',
    'learn.json',
    'CNAME',
    '.nojekyll'
  ], {
    dot: true,
    base: './'
  }).pipe(gulp.dest('dist'))
    .pipe($.size({title: 'copy'}));
});

// Compile and Automatically Prefix Stylesheets
gulp.task('styles', function () {
  // For best performance, don't add Sass partials to `gulp.src`
  return gulp.src([
      'site-assets/*.css',
    ])
    .pipe($.autoprefixer(AUTOPREFIXER_BROWSERS))
    .pipe(gulp.dest('dist/site-assets'))
    .pipe($.size({title: 'styles'}))
    .pipe(gulp.dest('.tmp/site-assets'));
});

// Scan Your HTML For Assets & Optimize Them
gulp.task('html', function () {
  var assets = $.useref.assets({searchPath: '{.tmp,.}'});

  return gulp.src('index.html')
    .pipe(assets)
    // Concatenate And Minify JavaScript
    .pipe($.if('*.js', $.uglify({preserveComments: 'some'})))
    // Concatenate And Minify Styles
    .pipe($.if('*.css', $.csso()))
    .pipe(assets.restore())
    .pipe($.useref())
    // Minify Any HTML
    .pipe($.if('*.html', $.minifyHtml()))
    // Output Files
    .pipe(gulp.dest('dist'))
    .pipe($.size({title: 'html'}));
});

// Clean Output Directory
gulp.task('clean', del.bind(null, ['.tmp', 'dist']));

// Build Production Files, the Default Task
gulp.task('default', ['clean'], function (cb) {
  runSequence('styles', ['jshint', 'html', 'images', 'copy'], cb);
});

// Run PageSpeed Insights
// Update `url` below to the public URL for your site
gulp.task('pagespeed', pagespeed.bind(null, {
  // By default, we use the PageSpeed Insights
  // free (no API key) tier. You can use a Google
  // Developer API key if you have one. See
  // http://goo.gl/RkN0vE for info key: 'YOUR_API_KEY'
  url: 'https://todomvc.com',
  strategy: 'mobile'
}));