/platypus.js

Load JavaScript&CSS with only one request.

Primary LanguageCSSMIT LicenseMIT

platypus.js

Experimental JavaScript loader that loads both CSS and JavaScript from one file resulting in only one request.

The idea is that you hide JavaScript code inside a CSS file. This means that the browser only has to load one file (the CSS) and platypus.js then extracts the JavaScript from the CSS file.

How to use

You include CSS in your HTML as you would normally do in the head:

<link rel="stylesheet" href="styles.css" type="text/css" />

The CSS file must include a #platypus-0 selector, with a background-image attribute that contains, as it's value, a base64 encoded JavaScript code:

#platypus-0 {
  display: none;
  background-image: url(data:text/js;base64,base64 encoded JavaScript code);
}

/*
Any other styles you have.
Your styles can also appear before the #platypus-X selector.
*/

Then right before the </body> you put platypus.js code:

<!--[if IE]>
<script src="platypus_ie.js"></script>
<![endif]-->
<script src="platypus.js"></script>

I recommend that you put it inline and that you use a minified version. For IE we have to include on extra file that provides base64 decoding functionality.

That's it, your JS will now be loaded from the CSS file.

note: originally content attribute was used, but IE can't read from it

#platypus-X ?!

You can have multiple CSS files. This allows you to have one common file for all of your page, and sub-page specific CSS files. Standard practise. And since putting #platypus {} in multiple files would override the previous occurrence, I have to somehow target different CSS files. Unfortunately this is currently the best solution I've came up with. The rule here is, that the first included CSS file must have a selector #platypus-0, the second #platypus-1 and so on.

OK, but how do I actually use this?

Since nobody will write JavaScript in base64 encoded format directly in CSS, some sort of deploy magic is needed. This part is, for now, left as an exercise for the reader. In the future I suppose there could be some "asset pipeline" modifier for the popular frameworks.

Is it safe to use?

Look at the current browser support and decide for yourself.

Browser support

Tested against all the experiments:

works

  • Chrome 26.0.1386.0 dev (OS X) & Version 24.0.1312.52 m (Windows 7)
  • Safari 6.0.2 (OS X & Windows 7)
  • Firefox 18.0.1 (OS X & Windows 7) doesn't work on example 2, but it doesn't matter
  • Internet Explorer 9 (Windows 7)
  • Opera 12.12 (OS X & Windows 7)
  • Dolphin on Android 4.0.3
  • Chrome on Android 4.0.3
  • stock browser on Android 4.0.3
  • Mobile Safari 6 (iOS 6.0.1 iPad 4)
  • Chrome on iOS 6.0.1 (iPad 4)

doesn't work

  • Internet Explorer 9 in IE8 compatibility mode (Windows 7)
  • Internet Explorer 8 and bellow

Now what?

I now have to fix the code so that it will work on as many browsers as possible. Then I have to create some benchmarks to see if this even makes sense.

Where can I learn more?

In this blog post. On the project page, where you can see some live demos. And in the old readme file here on GitHub (look into the experiments folder).

Platypus?

Well it's a funny animal that's half duck and half beaver (well not actually). And this project is trying to join two different things into one … so platypus.

License

Licensed under MIT. See LICENSE.md file for details.

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