I just read about an interesting library for using CSS selectors to apply Javascript behaviours, courtesy of a link from Ajaxian. The idea is simple: use CSS selectors in Javascript code to specify DOM nodes that Javascript event handlers should be bound to. This abstracts the event handling code away from the HTML. This gives cleaner code, though I’m not sure how useful it will be in practice, for two reasons:

• It will be slower than just writing the event handlers directly in the HTML. How much slower I haven’t measured, so this may not be a problem.
• I don’t write much Javascript directly (except when trying out new ideas). Instead I tend to generate it (along with HTML) from other sources, so achieving a separation between Javascript and HTML isn’t an issue for me.

However I don’t want to give a negative view of this library. I think it is really neat, and it has interesting similarities to Aspect–orientedprogramming (AOP). In AOP you change code by specifying places to add extra functionality. This library is changing HTML by specifying places to add extra functionality. If you squint the right way HTML and Javascript merge into one, so there seems to be a relationship here. I don’t know enough about AOP to know if this analogy opens up any interesting new directions, but I know people who do, and I hope they’re going to comment on this.