I’ve updated my JavaScript toolkit for building recursive-descent parsers to ES2015, and updated it to v2.0.1. It’s on npm and github. The readme explains how to use it.

I’ve also just found out that Visual Studio 2015 Update 1 supports TextMate grammars — and Canto34 produces them. So you can write yourself a language, and use its lexer inside Visual Studio. This makes it great for producing DSLs like custom configuration files and testing languages. You’ll want to use the canto34-syntax.js code to produce a .tmLanguage file, and install it into Visual Studio using this tutorial.