Ohm – A library and language for building parsers, interpreters, compilers, etc.
Compiler compilers are great, I love writing DSLs for my projects. I usually use yacc/lex, or write my own compiler (typically in go these days).However (and this is just me talking), I don't see the point in a javascript-based compiler. Surely any file format/DSL/programming language you write will be parsed server-side?