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A Few Words on JavaScript Redirect Cloaking

JavaScript cloaking is the (usually deceptive) use of redirecting a user to a different page with Java

-

Script. Because spiders do not execute JavaScript, this used to be an effective method to feed spam

to search engines. Most notoriously, BMW of Germany was briefly removed from the German Google

search engine index. Matt Cutts states in his blog (

http://www.mattcutts.com/blog/ramping-

up-on-international-webspam/

) that “

… our webspam team continued ramping up our anti-spam

efforts by removing bmw.de from our index …”

And, although search engines do not generally execute

JavaScript, they do look for this technique.

Using JavaScript to implement cloaking is not advisable in our opinion, because it is really only useful for

spamming — in contrast to IP delivery–based cloaking. It also requires a totally new page to be imple-

mented, whereas IP delivery–based cloaking can effect small changes in presentation, as you’ll see in

the examples.

The most trivial implementation of Java redirect cloaking is one that simply changes the location of a

page via JavaScript. Following is an example of JavaScript redirect cloaking code:

<script language=’javascript’>

<!--

document.location = ‘http://www.example.com/new_location.html’;

-->

</script>

In practice, different methods are used to obscure this code from a search engine’s view to make it more

difficult to detect. Because this method is almost always used for spamming, it is not discussed further.

The Ethical Debate on Cloaking

Very few areas of search engine optimization evoke as much debate as cloaking. Dan Thies states that

“

cloaking is a very risky technique

.” He also states that “

… the intent of cloaking is to deceive search engines

.”

This is a statement with which we do not entirely agree. In the opinion of many, there are legitimate uses

of cloaking. In practice, Yahoo! and MSN are relatively ambivalent regarding cloaking for non-deceptive

purposes.

Google, at the time of writing this text, states unequivocally in its terms of service that cloaking is not

within its guidelines regardless of intent. In its webmaster guidelines at

http://www.google.com/

support/webmasters/bin/answer.py?answer=40052

Google says that “

… cloaking … may result

in removal from our index

.”

Dan Thies states that “we do not consider IP cloaking to be an acceptable technique for professionals to

associate themselves with.” We take a milder view, especially in light of recent developments.

Recently, Google has also shown some ambivalence in actual enforcement of this principle. In particular,

the

New York Times

cloaks content. In short, it shows a search engine spider the entirety of a news article,

but only shows the abstract to a regular user. Human users must pay to be able to see the same content a

search engine can read. The

New York Times

uses IP delivery–based cloaking to do this.

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Chapter 11: Cloaking, Geo-Targeting, and IP Delivery

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