Wikipedia
SIM.JS
SIM.JS is an event-based discrete-event simulation library based on standard JavaScript. The library has been written in order to enable simulation within standard browsers by utilizing web technology.
SIM.JS supports entities, resources (Facility, Buffers and Stores), communication (via Timers, Events and Messages) and statistics (with Data Series, Time Series and Population statistics).
The SIM.JS distribution contains tutorials, in-depth documentation, and a large number of examples.
SIM.JS is released as open source software under the LGPL license. The first version was released in January 2011.