If you’re really crazy about optimizing page load time for your website, here’s an interesting trick. By abusing some parser quirks in common browsers like Firefox and IE, you can actually combine a CSS file and a Javascript file into a single download.

The technique relies on how CSS and JS parser behaves in IE and Firefox.

  • When the CSS parser encounters a HTML comment token (<!–) in CSS content, the token gets ignored.
  • When the JS parser encounters a HTML comment token (<!–) in JS content, the token is treated similar to the line comment (//) and hence the rest of the line following the HTML comment token gets ignored

So, if you can combine your JS and CSS files into a single file like the following, the Javascript parser will only see the Javascript code and the CSS parser will only see the CSS code:

<!-- /*
function t(){}
<!-- */
<!-- body { background-color: Aqua; }

You can still keep the files seperate for coding purposes, and then combine them at publish time or on the fly with a simple script, similar to what’s commonly done with Javascript obfuscation/compression.

Combine CSS with JS and make it into a single download – Link.