Back in the 60s, before synthesizers were commercially available, the BBC Radiophonic workshop was creating electronic music and sound effects for shows like Doctor Who. The BBC has now published a set of web-based simulations of some of this equipment, using just the Web Audio API of HTML5. The code and explanations are included.
Recreating the sounds of the BBC Radiophonic Workshop using the Web Audio API
Previously: Video: Radiophonic Style Electronic Music Improv