Truth is, Google is super awesome at getting into content that most search engine crawlers cannot find. GoogleBot is able to execute and run much of the JavaScript and AJAX it encounters but it is not perfect.
John Mueller in a Google Hangout on Google+ this past Friday answered a question around possibly using that as a way to hide content from Google. To hide links or content that you do not want Google to index in AJAX or JavaScript. This is what webmasters did years and years ago when Google was not able to crawl JavaScript.
But now, it is probably not recommended. Google can index most of it, and of course, it doesn't always get it right.
John Mueller said at the 14:10 mark into the video that it can be "on and off" for Google crawling and understanding JavaScript and AJAX. He said don't rely on blocking Google based on that and also, don't rely on Google indexing content there as well. Make sure you control what you can by really blocking Google from it or making it super accessible for Google to access it - depending on if you want the content indexed or not.
John said:
I’d say at the moment, it is still on and off but it is definitely heading in the direction that we are doing it more and more. So if you need to rely on it not being indexed then I wouldn’t rely Google kind of forgetting to crawl the JavaScript.
Here is the video embed:
Forum discussion at Google+.
