cgrantski - 1:03 pm on Jan 13, 2009 (gmt 0)

This is how I understand it, and I hope it adds the right amount of details to some of the generalities that are being stated here.

Bots may not RUN javascript in the usual sense, but many PARSE javascript for links and visit those links. Google's bot has done this for a long time. (Besides, remember that most good js-tracking systems have a 'noscript' line too.)

However most bots do not follow links that are for file types identifiable as images. This, not a javascript-following capability, is why people think javascript-tag tracking is "immune" to bots - javascript tagging generally relies on a request for a gif. Bots could easily see and follow these if they are programmed to do so, but they are usually programmed to ignore image links.

Some bots do request image file types, of course. It's a matter of how they are programmed, for example whether the programmer wants it to avoid being detectable as a bot because it doesn't request images. The analytics world had a major incident with one of these last year. Or, the bot might be an image collector, period.