What are the concrete risks of using custom HTML attributes?

Question

This subject turned into a heated discussion at the office, so I\'m interested to learn what you think.

We are working on a web app that only targets some specific b

Answer 1

If its a goal to maintain valid html4.0 strict, then it doesn't matter why you want to put in custom attributes, you are breaking the goal.

I think the question you need to be asking, is why do you need to break 4.0 strict to get the functionality you want: Anything that you could use a custom attribute for you, you could use a in an existing attribute:

...

could be:

...

it will be some extra cycles to parse all the class information, but so long as you don't put any css info on that class, it doesn't change display, doesn't put you in quirks mode, and doesn't get you in fights at work.