From vvvvjs.quasipartikel.at:
VVVV.js is “An open project, which aims to bring the visual programming language VVVV to your web browser.
In case you don’t know VVVV already: it’s a great piece of software for developing multi media applications using a visual programming language. Click through the VVVV website to get the details.
While the original VVVV runs as desktop application on Windows, VVVV.js tries to introduce all the great VVVV paradigms to the world of web browsers. In plain language this means: VVVV.js is a Javascript port of VVVV’s “runtime parts”, which enables your web browser to run VVVV files (or VVVV XML Code) on the client side.”