Litmus test to determine if javascript content is crawlable

Question

Already read this: How can I create links in javascript that are crawlable by search engines?

I make the assumption that if you view source on a page and can find content / links hidden by javascript contained within appropriate html tags after the page is finished loading the first time, then crawlers can find the content / links as well. Is this true? Also is there any special markup available that will highlight the content to a search engine?

Is finding the content in the html after initial page load an appropriate test whether the javascript on a page is Search engine friendly?

Answer 1

In general, JavaScript is not search engine friendly and by default you should assume that any content generated by it will be invisible to the search engines. Crawlable Ajax being the only definitive exception (which is supported only by Google).

However, there is a lot of talk of Googlebot processing JavaScript so although it has not been confirmed by Google it is possible that Google can find content created by JavaScript.

Notice how I keep saying Google? Unfortunately they aren't the only search engine. Additionally, crawlable Ajax is a terrible idea (more and more) and bad for accessibility and there are other search engines out there that won't find this content. So, as always, use progressive enhancement. Make sure that content can be reached without JavaScript being enabled.

Answer 2

John Conde's answer is good up to date information on how the crawlers read the page and the argument for making the page readable by everyone.

Since I mentioned a litmus test here's an improved version on the one I posted above before reading the articles in John's post. Let me know if I'm missing something, but I think this should work in most situations.

Litmus Test:

1. Enter - site:www.website.com/page.html for the page that contains the javascript in question at a search engine (using google's site search as an example).
2. Put quotes around a text phrase found only in the javascript manipulated content.
3. Search

Example: site:www.website.com/page.html "eat salmon to stay healthy"

If the phrase is highlighted in the returned description then you know the search engine found it. If you enter a quoted string, google seems to change the returned description from the one served by the page to the area that includes you quoted text.