A comprehensive reference guide to all functionality is required...

[LJ9999]

...and needs to be made easily accessible. I can't believe there is not such a document anywhere on the internet. Do people have to waste time figuring it all out?

[patrickhlauke]

what's missing from https://getbootstrap.com/docs/4.1/ that you'd like to see?

[herbalite]

Something like this?
https://hackerthemes.com/bootstrap-cheatsheet/

There are other results when searching the Web for Bootstrap 4 cheatsheet

[arechsteiner]

Thank you for mentioning my cheat sheet @herbalite.

FWIW I think the official documentation is pretty damn good. It fits the description "comprehensive reference guide" better than my cheat sheet.

[jipexu]

really ? the BS doc seems me better than numerous project on internet with long, dark and dry api list without any example ... Even if is not totally complete i agree with @arechsteiner the BS doc is good ! and cheat sheet is another useful tool !