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Optimizing static webpages with gulp

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22 Dec 2014

Recently I decided to create my own online portfolio/CV. Having a Github profile with all of your projects is nice but seems quite slow to inspect in my opinion. I therefore want to show off myself with a simple and light webpage. This doesn’t only relate to the design, which I’m not very good with by the way, but also in the resources you use: images, scripts (JavaScript), style sheets (CSS) and HTML pages.

Grunt or Gulp

gulp-grunt

I’m not going to discuss about which one is better but I already used Grunt in dominion and it works pretty well. I find it to be sometimes slow but my computer that may be my computer’s fault too. Gulp is all about piping files into plugins and it runs faster (at least in my case). It’s a streaming build system. Finally I could also use Brunch but that won’t be this time.

Gulp configuration file gulpfile.js is actually easier than a Gruntfile.js. It starts as any node module:

var gulp = require('gulp');

And then you add modules and tasks:

var gulp = require('gulp');
var jshint = require('gulp-jshint');
var stylish = require('jshint-stylish');

var from = {
  js: 'src/js/*.js'
};

gulp.task('jshint', function() {
  gulp.src(from.js)
  .pipe(jshint())
  .pipe(jshint.reporter(stylish));
});

This is just an example to lint the js code using a better reporter. You will have to install these modules with npm install.

Directory structure

.
├── README.md
├── fonts
│   └── fontawesome and stuff
├── gulpfile.js
├── images
│   ├── 404.png
│   ├── favicon.png
│   └── plogo.png
├── lib
│   └── js libs and stuff
├── css
│   └── css from libs and stuff
├── package.json
└── src
    ├── css
    │   ├── demo.css
    │   ├── tabs.css
    │   └── custom.css
    ├── index.html
    └── js
        └── app.js
  • lib dir contains js lib but you could also use bower to install them.
  • css dir contains css from lib/frameworks but you could, again, use bower.
  • src contain all the files that we are writing ourselves

Image optimization

When creating some webpages, the size of the resources is always what takes longer to load. Therefore optimizing images is always a good idea. We will be using gulp-imagemin. In addition to that we will also be using gulp-changed to only pipe images that were modified and therefore diminishing deploy time.

var changed = require('gulp-changed');
var imagemin = require('gulp-imagemin');

var from = {
  img: 'images/**/*[email protected](png|jpg|gif)',
  js: 'src/js/*.js'
};
var to = {
  img: 'images/'
};

gulp.task('imagemin', function() {
  return gulp.src(from.img)
  .pipe(changed(to.img))
  .pipe(imagemin())
  .pipe(gulp.dest(to.img));
});

We are chaging the images in place because we don’t need to save the same image twice if we are only going to use one of them. imagemin can also optimize svg files and support some options that should be taken into account depending of the kind of pictures you’ll be using on your site. You can check the readme for more help.

gulp-usemin

Now, we are going to minimize the js, the css and the html files all together by using the gulp plugin usemin. This is really useful because it will rename the tags used on your dev page as well, meaning that we won’t need to manually create an html page that includes your minified css and js files. Unfortunately we need to add some lines to help it:

<!-- build:css style.css -->
  <link rel="stylesheet" type="text/css" href="css/tabs.css" />
  <link rel="stylesheet" type="text/css" href="../css/normalize.css">
  <link rel="stylesheet" type="text/css" href="../css/skeleton.css">
  <link rel="stylesheet" type="text/css" href="css/custom.css"/>
  <link rel="stylesheet" type="text/css" href="../css/font-awesome.min.css"/>
<!-- endbuild -->

It’s very similar for the js:

<!-- build:js script.js -->
  <script src="../lib/modernizr.custom.js"></script>
  <script src="../lib/director.min.js"></script>
  <script src="../lib/cbpFWTabs.js"></script>
  <script src="js/app.js"></script>
<!-- endbuild -->

Our ìndex.html being located under src we need to reference the folders properly. One downside about usemin is that it rips off any comment including those targeting IE:

<!--[if lt IE 9]>
  <script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->

I might fix this myself in a pull-request. minifyHTML should not be ripping off these kind of comments because they’re not comments!

Once our html is fine, we should add the corresponding js to the gulpfile.js:

var usemin = require('gulp-usemin');
var uglify = require('gulp-uglify');
var minifyHTML = require('gulp-minify-html');
var minifyCSS = require('gulp-minify-css');

var from = {
  img: 'images/**/*[email protected](png|jpg|gif)',
  css: 'src/css/*.css',
  html: 'src/*.html',
  js: 'src/js/*.js'
};
var to = {
  img: 'images/',
  css: './',
  html: './',
};

gulp.task('usemin', function () {
  return gulp.src(from.html)
  .pipe(usemin({
    css: [minifyCSS(), 'concat'],
    html: [minifyHTML({empty: true})],
    js: [uglify(), 'concat']
  }))
  .pipe(gulp.dest('./'));
});

As you may have noticed we are creating the files at ., this is because having a gh-pages branch allows to Github to directly serve that index.html without further configuration.

Now we can do gulp imagemin, gulp usemin and we will be generating our site. But you can do better right. Gulp does have a built-in watch method. However we will not be using it because it doesn’t detect new or deleted files. We are therefore using gulp-watch plugin instead.

var watch = require('gulp-watch');

gulp.task('watch', ['default'], function() {
  watch(from.img, function() {
    gulp.start('imagemin');
  });
  watch([from.js, from.html, from.css], function() {
    gulp.start('usemin');
  });
});

gulp.task('default', ['jshint', 'imagemin', 'usemin']);

Please note that gulp.start will be removed in later versions. We could just copy the task code inside that function instead. It’s important to add default as a dependency so the generation will be executed at least once. Otherwise it will just wait for changes before generating anything.

Optimizing even more

If we run audits on the page with Chrome or Firefox, you may notice that most of the css is unused. What a shame! Fortunately we can fix this! We can rip off the unused css rules with gulp-uncss plugin. It also takes the html to detect what is not used. If some rules are not present in the index.html we must add an ignore array to the uncss call. This is documented on the Github page for gulp-uncss.

What we are going to do is simply strip off anything unused from the final style.css file instead of doing it with each file because it’s way faster. We are going to create a task named style depending on usemin so that the initial style.css file exists and we can modify it. We also need to update the default task to depend on style instead of usemin and, a new watch(from.css,...) and remove that from.css from the last watch(...):

var uncss = require('gulp-uncss');

gulp.task('style', ['usemin'], function() {
  return gulp.src(to.css + 'style.css')
  .pipe(uncss({
    html: [to.html + 'index.html']
  }))
  .pipe(gulp.dest(to.css));
});

gulp.task('watch', ['default'], function() {
  watch(from.img, function() {
    gulp.start('imagemin');
  });
  watch(from.css, function() {
    gulp.start('style');
  });
  watch([from.js, from.html], function() {
    gulp.start('usemin');
  });
});

gulp.task('default', ['jshint', 'imagemin', 'style']);

Finally I like to serve at the same time so I can launch gulp watch and then just keep working. This is very easy, we just need to add the gulp-connect plugin, create a task for it and add it as a dependency to the watch task:

var connect = require('gulp-connect');

gulp.task('connect', function() {
  connect.server();
});

gulp.task('watch', ['default', 'connect'], function() {

And voilà, happy coding.

The whole code source is available at Github. Thought it may change in the future.


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