This web page is a demonstration of the use of musical.js to play a long song with a lot of chords. Long sequences need to be fed to WebAudio a bit at a time to prevent overloading implementations, and music.js does this work for you. For a song that uses more ABC notation features, see minuet.
Here is the code for this page:
Minified, musical.js is about 17K, and it has no dependencies. It can also be used as an AMD or node.js modele.