Rangy
A cross-browser JavaScript range and selection library.
The future
I've started a discussion about the future of Rangy.
AMD
Rangy 1.3 has AMD support.
NPM
There is an official Rangy module on NPM called rangy.
Documentation
Documentation is in the GitHub wiki.
Bower
There is an official Rangy package for Bower with Rangy 1.2 and 1.3 versions, called rangy.