[cosarara]

Is it possible to fall back to a jpeg if the browser does not support js, wasm, or web workers? With a <picture> element, maybe?

I did some tests on my own server and found that for some reason it's quite fast when running on https, but super slow on insecure http. Not sure why that is, maybe the browser disallows something that's important here for insecure connections.

[niutech]

Yes, you can use <picture> to fall back to JPEG/PNG/WebP.

[cosarara]

https://cosarara.me/misc/jxljs/ in my test, it will simply fall back to jpeg, even if the jxl.js library is loaded (scroll down to Image with fallback).

[niutech]

This is because JXL.js doesn't support `<picture>` tags - there is no rationale for WASM-decoding JXL when you can provide a fallback in natively-decoded JPEG/PNG/WebP.

[cosarara]

The rationale would be that it might be more efficient to WASM-decode JXL than to download a JPEG, especially in pages with lots of images, but I would want a fallback if the browser does not support WASM.