WP Rocket | Simple LoadCSS Preloader

Deprecated

This plugin is deprecated and will be removed in the future.
It was coded back in 2019 when WpRocket did not have asynchronous support for CSS.
Although this plugin operates at a lower level (main php buffer), which helps apply loadsCSS to ALL styles regardless of whether they conform to wp_enqueue or not, we recommend instead using WpRocket’s system: Load CSS Asynchronously.

Description

Simple high performance plugin to enhance WP Rocket’s css output to use the loadCSS preload polyfill.
This will ensure any css being loaded via the page output is deferred, and utilizing a preload [rel] attribute.
Note: This will not affect admin pages. It’s designed only to process front-end pages.

It is recommended to enable the WP Rocket setting for “Optimize CSS”, which will provide your pages with inline Critical-CSS.
That way an unstyled flash is not seen on page load (if properly configured of course).

This plugin will boost your Lighthouse and PageSpeed Insight scores.

Plugin Mission

We hope that WP Rocket will implement this as a feature of their plugin.
The existing Load CSS Asynchronously only works for supported wp_enqueue styles, which not all plugins/themes properly utilize.
For normal users, we recommend using WP Rocket’s system instead of this plugin.

Requirements:

• If you intend for logged-in users to see the effect, you must enable WP-Rocket’s setting called “caching for Logged-In Users”
• Alternatively, you can run the plugin without WP-Rocket, despite it’s intended purpose. (>^.^)>

Features:

• FilamentGroup’s LoadCSS(v2.0.1) inline injector
  (optional – see settings page next to WP Rocket), triggered via wp_head
• High performance Regular Expression approach to process WP Rocket’s (php’s) output buffer, to replace stylesheets with the appropriate loadCSS syntax
• Option to enable the buffer processor when you don’t have WP Rocket installed.
  ** This will respect AMP pages, and Yoast Sitemap output (by not executing). No other considerations have been implemented.

No fluff. Just a robust loadCSS implementation.

You can see how it works, & measure the performance, with this(via repl.it): Run the Plugin’s code
Just paste your own page’s url or html into the appropriate variable @ the top.

And you can test this plugin’s regex as well: WordPress.com html – links filtered by regex

Github link is here: Click

Last tested with:

• WP Rocket 3.13.x
• WordPress 6.2.x

Dependencies

• WP Rocket (optional via settings)
• file_get_contents() php function (if included loadCSS lib is used via options — default = yes)