Autoptimize to allow optimizing whitelisted resources only (and more)

Although work is still ongoing on what will become Autoptimize 2.0, I thought I’d share an (API-only) feature that allows developers/ web agencies to only aggregate & minify a fixed set of known-good resources only. This whitelist-based optimization will allow for a more stable situation upon delivery of your project to customers, as the CSS/ JS of plugins that are installed by your customer will not be autoptimized, so the site is less likely to break by accident.
The following example-code shows how to tell Autoptimize to only aggregate & minify jquery.js and jquery-migrate.min.js;

function example_js_whitelist() {
return "jquery.js,jquery-migrate.min.js";

Using autoptimize_filter_css_whitelist allows you to accomplish the exact same things for CSS. The guys over at are already using autoptimize_filter_js_whitelist, so we must at least be doing something right there.
Some other new filters that might prove helpful;

  • autoptimize_filter_css_removables and autoptimize_filter_js_removables will allow you to specify which CSS or JS should actually be removed alltogether (Google Fonts, Emoji’s, … all in case you don’t like dequeuing off course)
  • autoptimize_filter_css_inlinesize allows you to specify up until how many characters of optimized CSS should be inlined instead of linked (can be useful for print CSS). Default value is 128, but I might bump that to 256 actually.
  • passing “true” to autoptimize_filter_css_fonts_cdn will tell AO to try to switch the font URL’s to your CDN
  • autoptimize_filter_cssjs_multidomain takes an array which can be used to tell AO that are also to be considered local domains and resources from those can be optimize (warning; as AO aggregates from the filesystem, this only works if the resources are actually local)
  • autoptimize_filter_cachecheck_do, autoptimize_filter_cachecheck_frequency and autoptimize_filter_cachecheck_maxsize can be used to control the wp-cronned cachechecker that will get triggered daily

Non-API improvements include performance optimizations, out-of-the box support for WPML subdomain-based language-variations and a whole heap of smaller improvements and bugfixes (e.g. the fact that if you have multiple title-tags, the optimized CSS would be injected in front of every one of those).
So yeah, I’d say we almost have ourselves a release. Only major thing still to go in; swapping the “look only in head” for an “include inline code” option. And testing of course, but that’s one area where I am looking at YOU, dear reader! Download the in-development version from GitHub and test away!