The officials notes "Webmasters who want to help Google crawl and index their content and/or generate the Instant Preview -- If you'd like to prevent content from being crawled or indexed for Google Web Search, traditional robots.txt directives remain the best method. To prevent the Instant Preview for your page(s), please see our Instant Previews FAQ which describes the "Google Web Preview" User-Agent and the nosnippet meta tag."
The officails suggests:
- Prefer GET for fetching resources, unless there's a specific reason to use POST.
You can test whether resources are blocked through Webmaster Tools "Labs -> Instant Previews."
To verify that you're not accidentally cloaking, you can use Instant Previews within Webmaster Tools, or try setting the User-Agent string in your browser to something like:
- Mozilla/5.0 (compatible; Googlebot/2.1;
- Remember to include important content (i.e., the content you'd like indexed) as text, visible directly on the page and without requiring user-action to display. Most search engines are text-based and generally work best with text-based content.
Google execs gave the following POST example of how they are improving crawling and indexing:
Examples of Googlebot's POST requests
- Crawling a page via a POST redirect
<html> <body onload="document.foo.submit();"> <form name="foo" action="request.php" method="post"> <input type="hidden" name="bar" value="234"/> </form> </body> </html>
In this step-by-step example, we improve both the indexing of a page and its Instant Preview by following the automatic XMLHttpRequest generated as the page renders.
- Google crawls the URL, yummy-sundae.html.
- Google begins indexing yummy-sundae.html and, as a part of this process, decides to attempt to render the page to better understand its content and/or generate the Instant Preview.
- During the render, yummy-sundae.html automatically sends an XMLHttpRequest for a resource, hot-fudge-info.html, using the POST method.
- The URL requested through POST, hot-fudge-info.html, along with its data payload, is added to Googlebot's crawl queue.
- Googlebot performs a POST request to crawl hot-fudge-info.html.
- Google now has an accurate representation of yummy-sundae.html for Instant Previews. In certain cases, we may also incorporate the contents of hot-fudge-info.html into yummy-sundae.html.
- Google completes the indexing of yummy-sundae.html.
- User searches for [hot fudge sundae].
- Google's algorithms can now better determine how yummy-sundae.html is relevant for this query, and we can properly display a snapshot of the page for Instant Previews.