Rocket Loader is in the news again. One of Cloudflare's earliest web performance products has been re-engineered for contemporary browsers and Web standards.

No longer a beta product, Rocket Loader controls the load and execution of your page JavaScript, ensuring useful and meaningful page content is unblocked and displayed sooner.

For a high-level discussion of Rocket Loader aims, please refer to our sister post, We have lift off - Rocket Loader GA is mobile!

Below, we offer a lower-level outline of how Rocket Loader actually achieves its goals.

Prehistory

Early humans looked upon Netscape 2.0, with its new ability to script HTML using LiveScript, and <BLINK>ed to ensure themselves they weren’t dreaming. They decided to use this technology, soon to be re-christened JavaScript (a story told often and elsewhere), for everything they didn’t know they needed: form input validation, image substitution, frameset manipulation, popup windows, and more. The sole requirement was a few interpreted commands enclosed in a <script> tag. The possibilities were endless.

Soon, the introduction of the src attribute allowed them to import a file full of JS into their pages. Little need to fiddle with the markup, when all the requisite JS for the page Continue reading