The guys at softwaredeveloper.com posted quite good article showing how not to use cloaking, div layering:
AJAX gives developers the ability to build dynamic web applications without the need for constant server side script parsing, enabling you to provide users with simulated “load on demand” sites. That means shorter page loading times, a sharp decrease in bandwidth consumption and more accessible information in general.
To help you as you incorporate the benefits of AJAX without making your site blind to search engines, we’ve assembled a guide of the best (and the worst) solutions for creating an AJAX page that maintains the ability to be indexed by Google. Here is our how to guide on getting Google and AJAX to play nice.
The Wrong Approach
The Little Things
AJAX allows you to incorporate a lot of innovative site design characteristics. Some designers take the AJAX craze too far, however, by incorporating AJAX to a degree that it hurts their site’s usability and accessibility. Here are a few of the most common problems.
* Making it too simple. Designing sites where AJAX controls everything and serves content on a single page can be a search engine ranking disaster, as your website will have only one URL for everything. Instead, be sure to offer unique sub-links and URLs for popular site features.
* Disabling browser controls. Since AJAX does not communicate with your browser’s history, simple actions like hitting your browsers back and forward buttons are rendered useless. Although you may not traverse your website via browser buttons, many users do. Make sure you’re not overdoing AJAX so much that users get lost in your website.
* Not using Google’s Webmaster Tools. These tools are a simply and reliable way to keep track of the pages of your website Google is indexing.
Perhaps the easiest (read laziest) solution is to just abandon AJAX altogether in favor of server side scripting languages such as PHP or Perl. While these languages are powerful enough to perform virtually every operation, they lack the same interactive feel that AJAX websites produce. Now we’re not saying you should completely avoid using server side scripting languages; however, for front-end pages requiring a lot of simple interaction with the consumer we’re all for AJAX.
The Right Approach
Here are a few general tips you should follow when developing a search engine friendly AJAX website.
* After you’ve established a non-AJAX working version of your website, go back and include an alternative AJAX enhancements where you desire.
It is extremely important to follow this methodology for widely used site features such as navigation bars. After all, if the user is unable to traverse the pages of your website, what is the point of offering content?
Excerpt from Progressive Enhancement with Ajax:
Pointless link – BAD!
Using the DOM – BETTER.
You can generate a degree of search engine recognition for your AJAX webpages by using the noscript element. The noscript element “allows authors to provide alternate content when a script is not executed.” For more information on implementing the noscript technique, check out this informative article.
Now that you have incorporated some of the pro search engine AJAX design recommendations, you can get the ball rolling for your website by submitting a Sitemap index file to Google. Sitemaps allow a “webmaster to inform search engines about URLs on a website that are available for crawling.” Keep in mind simply submitting a sitemap isn’t enough, you’ll need to engange in a combination of the previously mentioned techniques for the best results. For more information check out Sitemaps Wikipedia file.