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Web builders can create CSS class
and id names and use those names to identify divs and other page elements for
formatting. The CSS selectors that redefine XHTML tags must match the
predefined tags exactly, but class and id selector names are totally at the
discretion, ingenuity, and whim of the Web builder. However, it may not be the
best practice to follow whims in class and id naming.
After reading a series of articles
by Andy Clarke (of Stuff
and Nonsense and All That Malarkey) and Eric Meyer that address naming conventions for CSS classes and
ids, I began to think about the way I name classes and ids on my sites.
When you’re working on a Web page
and need to come up with an identifying name for a div, the natural temptation
is to use a name that describes the element’s page location. This approach
leads to class and id names such as the following:
These are all valid names for CSS
and XHTML classes and ids. They’re simple and descriptive, so they serve the
purpose of identifying the page element and its corresponding CSS style.
The problem is that such names
relate to a specific presentation of the content. They reference the position
of page elements in a particular page layout, and may be inappropriate and
confusing outside the context of that layout. And, these names don’t say
anything about the structure of the document content. There are better ways to
name your CSS classes and IDs.
True structural markup means
completely separating presentation/position information from the content—that
includes class and id names that appear in the markup.
The goal is for all markup to relate
information about the document’s structure rather than its presentation. This
facilitates reusing the content and markup in different presentation formats by
simply changing the CSS. When you think about it, it’s easy to see that class
and id names that refer to page position are inappropriate in presentation
formats such as audio. Therefore, structural naming names classes and ids by
their purpose in the document, not their location.
Taking a structural approach to
naming might produce class and id names such as the following:
These names are just as descriptive
as the presentational names, but they describe what the page element does,
instead of its location. The result is code that is much closer to the goal of
pure structural markup that designers can format for various presentation media
without changing the markup.
Even if you don’t plan to format
your Web page for presentation in other media, using structural naming can help
make future updates/redesigns easier. For example, structural naming eliminates
the confusion that would arise if a div with the id right-column moves to the left side of the page. Naming the div sidebar is much more appropriate, and
the name remains valid no matter which side of the page it’s on.
Andy Clarke looked at the code of 40
Web sites by builders with reputations for espousing standards-compliant Web
design. Although class and id names were far from uniform, some common names did
show up frequently. Here’s a sampling of the most common class/id names:
For the full list, see this table of most popular naming conventions.
Do these common class and id names
constitute an emerging standard or the beginnings of a widely accepted
convention? I don’t know, but I hope so. I welcome a set of standard names for
the common page elements we see every day. Also, using standardized naming
conventions would make it easier to find and update common page elements—especially
when you need to move from site to site, working on sites that different
builders created at different times.