Warning about bad formats order or maybe some reordering of outputs object?

[zachleat]

If you use formats: ["jpeg", "webp", "avif"] the generateHTML utility will generate markup with <source> in the wrong order.

There is some intentional behavior there that we wouldn’t want to destroy, maybe you’d want "jpeg", "png" or "png", "webp". At this point in time "avif" should never be last though. And it’s very unlikely "webp" would come after "jpeg" or "png". I doubt you’d want "webp" before "avif" too.

So, not sure. I think warnings are in order so that we can lean towards teaching instead of using automation to protect from requiring the knowledge.

[zachleat]

Here’s a rule list I think would be useful:

• avif should always be before jpeg, webp, and png.
• webp should always be before jpeg and png
• png should be preferred to jpeg when the image has transparency separate issue on Handle images with an alpha channel #105
• svg should always be first for super complex large SVG we may want to use raster instead

Are there others?

[AleksandrHovhannisyan]

Hey, hope it's cool to chime in. My only concern with a warning would be that it might get lost in the output/people might not notice it easily. Is throwing an error too heavy-handed? Might make sense to auto-sort the formats to prioritize webp/avif as a best practice.

[zachleat]

Ah @AleksandrHovhannisyan I do think we should auto-sort for those small set of rules (paired with an opt-out) but also show a warning that a re-sort happened?

[AleksandrHovhannisyan]

Yup, that makes sense!

[AleksandrHovhannisyan]

@zachleat Are you accepting PRs for this enhancement? I'd be happy to contribute one if you think the scope is manageable, and unless you'd prefer to tackle it yourself.

Haven't dived back into the code yet, but I'm thinking it should be simple. We can have a map from extensions to numeric priorities and then use it to sort the formats array. Is there already a standard way of communicating warnings in the plugin?