I’ve been working with a website for a few months now, and I noticed a peculiar thing. About half of the more prominent pages were missing from Google’s index while many of the obscure ones were making it. It didn’t make any sense.

But I just figured out why. The site owner was using a JavaScript menu system under his site-wide header. I thought it was nothing but HTML and style sheets. But when I checked the source, there I saw it.

In this case, it wasn’t that big a deal because the owner really only used the site in his store. But had he been more dependent on search engines, the results would have been disastrous. In most cases, Google cannot and will not follow links in JavaScript menus.

That doesn’t mean you shouldn’t use them. It means you had better have a damn good xml sitemap – because without one, every page that is only linked-to from your menu will not be in Google’s index and not be in any SERP. Not only is this bad for traffic, but Google also ranks sites higher that have more content – and if Google can’t see those pages, all that hard work writing that content goes down the toilet!