Does Google's Crawler Index Asynchronously Loaded Elements?

I've built some widget for websites which is asynchronously loaded after the page is loaded: ...

Solution 1:

No. You have to set up static mirror pages for asynchronous content. See here: http://code.google.com/web/ajaxcrawling/docs/getting-started.html

Solution 2:

Things have evolved since then:

• Google crawls and indexes all content that was injected by javascript.
• Google even shows results in the SERP that are based on asynchronously injected content.
• Google can handle content from httpRequest().

(...)

• Dynamically updated meta elements get crawled and indexed, too.

Source: http://www.centrical.com/test/google-json-ld-and-javascript-crawling-and-indexing-test.html