Why does twitter's share button add data-twttr-rendered="true" to my body tag?

Question

Just curious. Why would it need access to that part of the DOM, and not just the part it's manipulating?

Answer 1

Seems to be that the twitter button's render callback needs to know if the whole page has been rendered (especially if you have more than one on a page), and the body tag is an obvious place to store that information by means of an attribute...

Tweet button docs: https://dev.twitter.com/docs/tweet-button

Look up also twttr.TweetButton and its method render()

For confirmation have an explore of this code: http://platform.twitter.com/widgets.js (do a search for data-twttr-rendered to see it used - it is minified unfortunately however!)