I would like to find a javascript parser that can handle and evaluate simple expressions. The parser should be able to evaluate the regular mathematical expressions, and sup
See this tutorial for how to build arbitrary parsers/compilers. (Basically it automates the construction of recursive descent parsers from grammars, meaning you can change your expression syntax easily). The whole tutorial is done in JavaScript, so it applies directly to you.
http://www.bayfronttechnologies.com/mc_tutorial.html