Google PageSpeed says: Remove unused JS and CSS, estimated savings: 0.75s and 0.6s. To improve my FCP and Speed Index.
1/ CSS: I found this website which works fine https://purifycss.online except that cover images now all look the same with a random image from my site. weird! anybody knows how to correct this behaviour?
2/ I need to find a purify js website that generates a file easily so I can include it on my site. Didn’t search much but was wondering if anyone has a clue?
By the way, I’m uploading files on netlify (which works great) since I’m using the free plan of digital press. http://soundsirius.digitalpress.blog/
You need to proceed with caution removing JS, as it may well be better performance overall to share one (minified) JS file across your site.
Assuming cache headers are set OK, your readers’ browsers will cache the JS file first time around (i.e. from the page they land on) and then use the cached version for subsequent page loads as they navigate around.
If each page of your site contained unique, perfectly-tuned JS just for that individual page, you may well be costing bandwidth - and performance - overall, because you could otherwise be leveraging browser cache more efficiently.
The exception to that is if your theme is loading a lot of large unused libraries or code relating to features that you don’t use anywhere on your site. In that case, you should remove that stuff.
If purifycss is breaking your cover images, then I’m not sure it’s working fine. 