What was meant as a quick test of rel-nofollow once again (inspired by Michelle’s post stating that nofollow’ed comment author links result in rankings), turned out to some interesting observations:
- Google uses sneaky JavaScript links (that mask nofollow’ed static links) for discovery crawling, and indexes the link destinations despite there’s no hard coded link on any page on the whole Web.
- Google doesn’t crawl URIs found in nofollow’ed links only.
- Google most probably doesn’t use anchor text outputted client sided in rankings for the page that carries the JavaScript link.
- Google most probably doesn’t pass anchor text of JavaScript links to the link destination.
- Google doesn’t pass anchor text of (hard coded) nofollow’ed links to the link destination.
As for my inspiration, I guess not all links in Michelle’s test were truly nofollow’ed. However, she’s spot on stating that condomized author links aren’t useless because they bring in traffic, and can result in clean links when a reader copies the URI from the comment author link and drops it elsewhere. Don’t pay too much attention on REL attributes when you spread your links.
As for my quick test explained below, please consider it an inspiration too. It’s not a full blown SEO test, because I’ve checked one single scenario for a short period of time. However, looking at its results within 24 hours after uploading the test only, makes quite sure that the test isn’t influenced by external noise, for example scraped links and such stuff.
On 2008-02-22 06:20:00 I’ve put a new nofollow’ed link onto my sidebar: Zilchish Crap
<a href="http://sebastians-pamphlets.com/repstuff/something.php" id="repstuff-something-a" rel="nofollow"><span id="repstuff-something-b">Zilchish Crap</span></a>
<script type="text/javascript">
handle=document.getElementById(‘repstuff-something-b’);
handle.firstChild.data=‘Nillified, Nil’;
handle=document.getElementById(‘repstuff-something-a’);
handle.href=‘http://sebastians-pamphlets.com/repstuff/something.php?nil=js1’;
handle.rel=‘dofollow’;
</script>
(The JavaScript code changes the link’s HREF, REL and anchor text.)
The purpose of the JavaScript crap was to mask the anchor text, fool CSS that highlights nofollow’ed links (to avoid clean links to the test URI during the test), and to separate requests from crawlers and humans with different URIs.
Google crawls URIs extracted from somewhat sneaky JavaScript code
20 minutes later Googlebot requested the ?nil=js1 URI from the JavaScript code and totally ignored the hard coded URI in the A element’s HREF:
66.249.72.5 2008-02-22 06:47:07 200-OK Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html) /repstuff/something.php?nil=js1
Roughly three hours after this visit Googlebot fetched an URI provided only in JS code on the test page:
handle=document.getElementById(‘a1’);
handle.href=‘http://sebastians-pamphlets.com/repstuff/something.php?nil=js2’;
handle.rel=‘dofollow’;
From the log:
66.249.72.5 2008-02-22 09:37:11 200-OK Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html) /repstuff/something.php?nil=js2
So far Google ignored the hidden JavaScript link to /repstuff/something.php?nil=js3 on the test page. Its code doesn’t change a static link, so that makes sense in the context of repeated statements like “Google ignores JavaScript links / treats them like nofollow’ed links” by Google reps.
Of course the JS code above is easy to analyze, but don’t think that you can fool Google with concatenated strings, external JS files or encoded JavaScript statements!
Google indexes pages that have only JavaScript links pointing to them
The next day I’ve checked the search index, and the results are interesting:
The first search result is the content of the URI with the query string parameter ?nil=js1, which is outputted with a JavaScript statement on my sidebar, masking the hard coded URI /repstuff/something.php without query string. There’s not a single real link to this URI elsewhere.
The second search result is a post URI where Google recognized the hard coded anchor text “zilchish crap”, but not the JS code that overwrites it with “Nillified, Nil”. With the SERP-URI parameter “&filter=0″ Google shows more posts that are findable with the search term [zilchish]. (Hey Matt and Brian, here’s room for improvement!)
Google doesn’t pass anchor text of nofollow’ed links to the link destination
A search for [zilchish site:sebastians-pamphlets.com] doesn’t show the testpage that doesn’t carry this term. In other words, so far the anchor text “zilchish crap” of the nofollow’ed sidebar link didn’t impact the test page’s rankings yet.
Google doesn’t treat anchor text of JavaScript links as textual content
A search for [nillified site:sebastians-pamphlets.com] doesn’t show any URIs that have “nil, nillified” as client sided anchor text on the sidebar, just the test page:
Results, conclusions, speculation
This test wasn’t intended to evaluate whether JS outputted anchor text gets passed to the link destination or not. Unfortunately “nil” and “nillified” appear both in the JS anchor text as well as on the page, so that’s for another post. However, it seems the JS anchor text isn’t indexed for the pages carrying the JS code, at least they don’t appear in search results for the JS anchor text, so most likely it will not be assigned to the link destination’s relevancy for “nil” or “nillified” as well.
Maybe Google’s algos dealing with client sided outputs need more than 24 hours to assign JS anchor text to link destinations; time will tell if nobody ruins my experiment with links, and that includes unavoidable scraping and its sometimes undetectable links that Google knows but never shows.
However, Google can assign static anchor text pretty fast (within less than 24 hours after link discovery), so I’m quite confident that condomized links still don’t pass reputation, nor topically relevance. My test page is unfindable for the nofollow’ed [zilchish crap]. If that changes later on, that will be the result of other factors, for example scraped pages that link without condom.
How to safely strip a link condom
And what’s the actual “news”? Well, say you’ve links that you must condomize because they’re paid or whatever, but you want that Google discovers the link destinations nevertheless. To accomplish that, just output a nofollow’ed link server sided, and change it to a clean link with JavaScript. Google told us for ages that JS links don’t count, so that’s perfectly in line with Google’s guidelines. And if you keep your anchor text as well as URI, title text and such identical, you don’t cloak with deceitful intent. Other search engines might even pass reputation and relevance based on the client sided version of the link. Isn’t that neat?
Link condoms with juicy taste faking good karma
Of course you can use the JS trick without SEO in mind too. E.g. to prettify your condomized ads and paid links. If a visitor uses CSS to highlight nofollow, they look plain ugly otherwise.
Here is how you can do this for a complete Web page. This link is nofollow’ed. The JavaScript code below changed its REL value to “dofollow”. When you put this code at the bottom of your pages, it will un-condomize all your nofollow’ed links.
<script type="text/javascript">
if (document.getElementsByTagName) {
var aElements = document.getElementsByTagName("a");
for (var i=0; i<aElements.length; i++) {
var relvalue = aElements[i].rel.toUpperCase();
if (relvalue.match("NOFOLLOW") != "null") {
aElements[i].rel = "dofollow";
}
}
}
</script>
(You’ll find still condomized links on this page. That’s because the JavaScript routine above changes only links placed above it.)
When you add JavaScript routines like that to your pages, you’ll increase their page loading time. IOW you slow them down. Also, you should add a note to your linking policy to avoid confused advertisers who chase toolbar PageRank.
Updates: Obviously Google distrusts me, how come? Four days after the link discovery the search quality archangel requested the nofollow’ed URI –without query string– possibly to check whether I serve different stuff to bots and people. As if I’d cloak, laughable. (Or an assclown linked the URI without condom.)
Day five: Google’s crawler requested the URI from the totally hidden JavaScript link at the bottom of the test page. Did I hear Google reps stating quite often they aren’t interested in client-sided links at all?
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