FESI (Free EcmaScript Interpreter) implements few language extensions and try 
to follow the standard as much as possible. 
This is unlike most implementation of JavaScript, which are unfortunately very
incompatible between them. 
For the core language definition you can refer to the ECMA 262 standard. 

WWW: http://home.worldcom.ch/jmlugrin/fesi/

- Leo Kim
leo@florida.sarang.net