Looking at the source code of a popular, well-maintained and documented library is incredibly helpful towards illustrating best practices and design patterns. I find it so much easier to see the benefits of various patterns when I see them in practice.
Very cool project! Out of curiosity, after reading the story section in the README, I thought of Sikuli. Would JavaScript bindings to the Sikuli API meet your desired use case, or are you looking to provide other functionality, improve performance, etc?