CSS spinner with javascript

Conclusions

• While the used construction of spinner and javascript is made in a progressive enhancement way, all kinds of visitors/devices are served (as far as I can see).
  • A text-only browser (and the Google-bot) doesn't see the spinner (nor the images): no problem.
  • If CSS is disabled, there is no spinner and the spinner-script is inoperative; images will appear as soon as they are downloaded.
  • If CSS is enabled and Javascript disabled, then fast loaded images and missing images don't have a spinner; only slow loading images get a spinner.
  • If CSS and Javascript are both enabled, then that's the same and the visitor can enjoy a smooth fade-in of slow loaded images.
• The spinner CSS styles are small (3.5kB uncompressed), the spinner javascript too (1.5kB uncompressed). They can be minified and included in existing stylesheets and javascript-files; then they don't need an extra http-request.
• The CSS-validator and HTML-validator can appreciate the code.
• Testing on a pc (Win-7) is positive for Firefox, Chrome, Opera en Internet Explorer-11. On mobile devices I couldn't test, but according to the simulations in Firefox and Chrome Developer Tools I don't expect problems. The only thing is extremely small images, then the spinner could overflow the imgBox; but small images are fast downloaded, and shouldn't need a spinner. Anyway, the Google's Mobile Friendly Test is satisfied.
• Google's PageSpeed Insights tell that the previous page has a speed score of 99 out of 100 according to the Lighthouse lab data. More about this on the next page .

And of course the are lots of ways to refine these basic ideas.
So far, so good.

All well and good - but, but, but ...

"On my PC I don't see any spinner in the imgBoxes on this page!"
True - and all HTML, CSS and javascript is exactly the same as on the previous page...

"Why does the 'empty cache / hard reload' not work any more?"

Has the spinner evaporated in the cloud?