I have a community website that is broken down into around 100 categories, each containing numerous pages. The categories only go 2 levels deep, top level and subcategories. I currently display the entire tree of categories completely expanded on every page in the site as a navigational aid, and I would prefer to keep it that way. However, it's my understanding that having links to 100+ category pages from every page in the site tends to diminish the pagerank of the home page, which of course you want to be high. It seems to me that it would benefit the pagerank of the site if google did not see the links to the 85 or so 2nd level categories, EXCEPT from the corresponding top level category page. So I am thinking about using javascript to write the <A tags on 2nd level category links to better focus the PR toward the homepage of the site. In other words, my users would still see links to Blue Hats and Green Hats from every page in the site, but google would only see links to Blue Hats and Green Hats from the Hats category page. So my 2 questions are, from a pagerank optimization standpoint does it make sense to alter my linking structure in that manner (linking to fewer internal pages from the global nav), and, if so, might google penalize me for hiding my links from it?
I would recommend linking to each section from each page on the site. Then your index page from each section can link to the pages in that section as well as the homepage and the main sections as well. The key is that every page on the site links to the homepage and a few important pages. If you link to all the pages from every page your site will be quite flat and it is hard for search engines to pick out the best bits. If you want to show different things to search engines than visitors then use a javascript menu with <noscript> tags for the search engines.
Dave: Thanks for your quick reply. Putting an end to the flattening effect you mentioned is exactly what I'm trying to achieve. At the same time, I'd like to continue to show my users a completely expanded hierarchy to navigate through. If it were collapsed it just would not be as easy to use. Also since I would be using javascript to write only the beginning <A tag, there would be no need for a <noscript> area because the text within the links would still be visible without javascript. Here's a simplified example: <a href="/hats">Hats</A><BR> <script>document.write('<a href="/hats/blue">')</script> Blue Hats</A><BR> Code (markup): Of course, on the hats page and all of its child pages, there would be google-visible links to all the child pages of hats. So to google it would appear as if hats were "expanded" on those pages.
I think your idea will work but I am not sure about the way you propose to hide the links from search engines using javascript. To me this is similar to cloaking but using client side script rather than server side. I would recommend using a good menu like milonic.com or similar.