When Validation Becomes Unimportant

Published on Jun 16, 2008 (updated Feb 5, 2024), filed under development (feed). (Share this on Mastodon or Bluesky?)

This and many other posts are also available as a pretty, well-behaved ebook: On Web Development.

Validation becomes unimportant only once you’re ahead of the game. Even then, truly mastering HTML and CSS, it’s best to stick with valid markup and styling. Improving latency might constitute the only exception—if at all.

The motivation to point this out stems from several discussions I had that “deprioritize” validation in order to save bits and bytes [something I later referred to as the hyper-optimized way of writing HTML]. Alas, the context includes use of font elements, layout tables, and the like, and as you may relate, talking about invalid markup in order to save load time in this environment is kind of silly. Therefore I repeat the statement above: Consider “invalidating” your documents and style sheets only for the sake of load time, once you proved to be a master.

Everything else is counter-productive. Validation fulfills several important purposes, one of them being that it drives learning. Let me tell you a short story: Through validation I probably learned the most about writing markup and style sheets, even though at the beginning, I still tortured the documents I wrote. Coming from that experience, I absolutely advise against using invalid HTML before a point of mastery.

There are many other things to address before dropping code that isn’t strictly necessary, but still required by the spec. Using markup according to its semantics can save bytes. Careful consideration of IDs and classes (including spare use of microformats) can save bytes. Questioning elements, referring to “divitis” and certain meta elements, can save bytes. Proper use of HTML (instead of XHTML) can save bytes. And the list goes on, including many additional performance measures unrelated to HTML.

Once you’re there you might say “okay, now let’s help the user once more and improve performance by pushing things a little bit further.” Not a second earlier. Don’t. And please don’t put a beginner the idea into their head that invalid HTML was good for performance. That would be a bogus claim, a harmful claim, and our industry would never recover from the resulting increase in incompetence. (Uh.)

About Me

I’m Jens (long: Jens Oliver Meiert), and I’m a web developer, manager, and author. I’ve worked as a technical lead and engineering manager for small and large enterprises, I’m an occasional contributor to web standards (like HTML, CSS, WCAG), and I write and review books for O’Reilly and Frontend Dogma.

I love trying things, not only in web development and engineering management, but also in other areas like philosophy. Here on meiert.com I share some of my experiences and views. (I value you being critical, interpreting charitably, and giving feedback.)