Custom attributes - Yea or nay?

Question

Recently I have been reading more and more about people using custom attributes in their HTML tags, mainly for the purpose of embedding some extra bits of data for use in ja

Answer 1

The easiest way to avoid use of custom attributes is to use existing attributes.

use meaningful, relevant class names.
For example, do something like: type='book' and type='cd', to represent books and cds. Classes are much better for representing what something IS.

e.g. class='book'

I have used custom attributes in the past, but honestly, there really isn't a need to for them if you make use of existing attributes in a semantically meaningful way.

To give a more concrete example, let's say you have a site giving links to different kinds of stores. You could use the following:

Molly's books
James' Music

css styling could use classes like:

.store { }
.cd.store { }
.book.store { }

In the above example we see that both are links to stores (as opposed to the other unrelated links on the site) and one is a cd store, and the other is a book store.