jsfx : This is a javascript library (with frontend) for sound effect generation.
Band.js : An interface for the Web Audio API that supports rhythms, multiple instruments, repeating sections, and complex time signatures.
howler.js : howler.js is an audio library for the modern web. It defaults to Web Audio API and falls back to HTML5 Audio.
meSpeak.js : meSpeak.js (modulary enhanced speak.js) is a 100% client-side JavaScript text-to-speech library
meSing.js : meSing.js is a JavaScript singing synthesis library that uses the Web Audio API's DSP capabilities in conjunction with the meSpeak.js speech synthesis...
The Javascript Sound Kit is a wrapper around the ActionScript Sound Object, it makes it possible to use the Sound Object in Javascript the same way you do it in ActionScript.