You dont have javascript enabled! Please enable it! What Is Cloudflare Rocket Loader? A Complete Guide Is Here - CHARBEL NEMNOM - MVP | MCT | CCSP | CISM - Cloud & CyberSecurity

What Is Cloudflare Rocket Loader? A Complete Guide Is Here

4 Min. Read

Is your website losing users because of slow-loading content or glitches like stalled animations or missing photos? The Cloudflare Rocket Loader can help.

When users of your website see big blank boxes with a tiny x in the upper right-hand corner or can’t access key information, they tend to surf to the next site. This means you lose business.

The culprit is usually an Ajax or Javascript code, which tends to block content or slow its loading time to a crawl. Cloudflare Rocket Loader prioritizes the content of your website by deferring any Ajax or Javascript code loadings until your pages are rendered.

In this complete guide, we’ll dive into Cloudflare Rocket Loader™ all features and capabilities.

What is Cloudflare Rocket Loader?

Cloudflare rocket loader is a tool included in any free or paid version of Cloudflare. Its purpose is to speed up the load time of your website by loading Javascript last.

How Does Cloudflare Rocket Loader Improve Metrics —

Unless your site is completely Java or Ajax based, you can expect to see immediately improved performance metrics when it comes to:

  • Time to First Paint (TTFP)
  • Time to First Contentful Paint (TTFCP)
  • Time to First Meaningful Paint (TTFMP)
  • Document Load

This result is a much faster loading time for your users, ensuring they see crucial content such as text and images first.

How Cloudflare Rocket Loader Works

Cloudflare works by rewriting all javascript types (text/javascript) to the app’s language, rocketscript (text/rocketscript.) Browsers cannot recognize text/rocketscript, so it defaults to loading what it can.

To have Cloudflare perform this function, you simply set it to automatic. Your browser will then ignore any Javascript code and all Javascript tags, including those that may have been in the cache.

Cloudflare and Browser Cache — Cloudflare will also check to see if any loading Javascript files are already in your browser’s cache and prevent them from being served again. Cloudflare ensures that Javascript files are downloaded asynchronously rather than as one big linear file.

How Cloudflare Rewrites Javascript Files

Javascript slows down your website load in the first place because it is typically just one big scrolling file.

The browser interprets your site’s download according to the “rocket.min.js” file installed in your website’s header. This file rewrites all javascript tags to rocketscript.

Cloudflare then moves these rewritten rocketscript text files to its content delivery network (CDN), where they are compressed into minified files and defined as smart groups.

How Cloudflare Prioritizes Site Upload

When you enable Cloudflare Rocket Loader, a file called (rocket-loader.min.js) is added to your website.

The min.js file determines what should be loaded first and then seeks out any retranslated text/rocketscript resources that have been converted from text/javascript.

Cloudflare also speeds up load time by detecting JavaScript tags in your browser cache and blocking them from loading.

Cloudflare File Compression

Cloudflare combines JavaScript files outside of the cache into compressed groups of files served with GZIP.

The app also clusters external resources, such as Facebook Scripts and Adsense, and groups them as external files. This allows Cloudflare to serve files to the browser in the order of your site’s HTML document.

Cloudflare and Broken Animations

One of the main criticisms of Cloudflare rocket loader is that it breaks Ajax and javascript animations. This is because the attribute value of any text converted from Ajax to Java is nil.

The only way to resolve this issue is to use CSS animations instead of java.

Cloudflare Breaks Java Slider Animations

The Cloudflare speed app does not work with java slider animations, and your viewer will likely be stuck looking at an icon that says the images are loading, but then they never do. This is due to the strict HTML validation required by our Cloudflare account.

Cloudflare Breaks Xenforo Software

Cloudflare Rocket Loader has a particularly adverse effect on Xenforo, forum software that is Ajax-based. This is because it cannot cancel an earlier rendering of the site’s individual scripts.

CSS Works Best With Cloudflare Rocket Loader

Users of Cloudfare Rocket loader experience a dramatic improvement in load time, as long as you are not Ajax or java-based.

The advice is to change all of your animations to CSS animations, but if you are not willing or able to do this, then the Cloudflare rocket loader may not be the best choice.

Cloudflare Browser Compatibility

Cloudflare rocket’s browser compatibility depends on whether or not you have a Free, Pro, Business, or Enterprise plan.

Cloudflare Rocket Loader™ Browser Compatibility
Cloudflare Rocket Loader™ Browser Compatibility

The Free Plan works with desktop browsers installed in Windows 7 or OS X 10.6 or later. Incompatible browsers include Windows XP and Android 3.0.

Using the Cloudflare rocket free account, you can safely run a lightweight virtual browser such as:

  • Android 3.0 (Honeycomb) and later
  • Firefox 2
  • Google Chrome v5.0.342.0
  • Internet Explorer 7 and later
  • Opera 8 (with TLS 1.1 enabled)
  • Safari 2.1
  • Windows Phone 7

Disabling Rocket Loader

How to disable Cloudflare Rocket Loader?

If you are running Ads on your site, we recommend keeping the Rocket Loader functionality turned off, as it might conflict with your Ad code and hurts your Ad earnings. This is because the Rocket Loader will load js scripts asynchronously and that hinders any Ad scripts that you’ve put on the page.

Once you have enabled Rocket loader, you may need to disable it, possibly to replace javascript code with CCS code or keep your website operative while determining the next steps to speed up page load time.

Cloudflare Rocket Loader™
Cloudflare Rocket Loader™

These are the steps to disabling Rocket Loader from the Cloudflare dashboard:

1) Go to the Cloudflare Dashboard and search for your website (you can have more than one website in your Cloudflare account).

2) Click on Overview and then look for the sub-menu Speed.

3) Click on Optimization.

4) Scroll down to find the option Rocket Loader to enable or disable it.

To enable the Rocket loader again, perform these steps in reverse.


Cloudflare works best with websites that juggle a lot of external scripts. If your website uses Javascript animation or Ajax scripts, it can cause your site to go 404.

I hope you found this article helpful.

Thank you for reading my blog.

If you have any questions or feedback, please leave a comment.

-Charbel Nemnom-

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About the Author
Charbel Nemnom
Charbel Nemnom is a Senior Cloud Architect with 21+ years of IT experience. As a Swiss Certified Information Security Manager (ISM), CCSP, CISM, Microsoft MVP, and MCT, he excels in optimizing mission-critical enterprise systems. His extensive practical knowledge spans complex system design, network architecture, business continuity, and cloud security, establishing him as an authoritative and trustworthy expert in the field. Charbel frequently writes about Cloud, Cybersecurity, and IT Certifications.

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