Thanks to wasm, you don't have to bow to Google's whim and can choose to include jpeg xl support on your websites if you want: https://github.com/niutech/jxl.js
I believe so. This line in the source code means it'll only attempt the decoding if an img element for a .jxl image url fails to load.
If you're on safari, you can verify it by going to the demo page at https://niutech.github.io/jxl.js/ and inspect the image element. If the src attributes contain blob, then it's decoded using the wasm decoder. If the src attribute contains url to a .jxl file, then it's decoded natively.
I read "wasm" as per "wasp" -- white, Anglo-Saxon -- and then my brain create "men" because Protestant didn't make sense. And I continued to read the sentence until context didn't make sense.
But it still kind of does.
(Yes, I know web assembly is a thing. Just making conversation.)