It's primitive. It hasn't been tested on anything other than chrome. The UI has no documentation. It's got some growing up to do, but it's still fun to play around with.
Here it is: Web Guitar Demo
Load the example "Moonlight sonata" and press play.
Hint: clicking above the strings in the editor will toggle between 4, 8, 16, 1, 2 which is the reciprocal of the duration of the note. Also, after clicking on a string, you can navigate the editor using the arrow keys.