Lint warnings for web content developers/authors

As suggested in 6ac112db998aaae568aaf0b47de2c6f7f9512b92, would it be helpful to emit warnings when invalid things such as aria-labelledby="" are encountered?

• Should it just do it, or should this be a separate mode?
• If the error has already been reported, should it be reported again (e.g. during a scan after a mutation)? (Probably not—could flag the first scan? But then that might miss the error, as it could be added by a mutation, so should a record of the errors be kept?)

Update (2019/08/11): I’m leaning towards it always linting, and exposing some icons in the pop-up at least (maybe even a flag on the icon?) In order to stop repeated results, it could take note of the selector computed for an element, as this should remain constant across certain page changes.

[carmacleod]

Lack of a main region?

Absolutely, flag lack of a main region, mostly because main is the most important landmark, but also if there’s, say, a header and a footer and no main, then there must be a big chunk of:

Content that is outside of a landmark region.

One exception that I noticed was google, which has only a single “search” landmark, and no main… which kind of makes sense… (nothing else on the page is in a landmark, but it’s a very sparse page)

[matatk]

Finally started to address this, with just one simple check, in #410 😃.