When jq came out about a decade ago I fell victim to a nerdsnipe and decided to try and mimic its syntax by building a parser in javascript: https://github.com/tjoekbezoer/jsq. Never completely finished it, nor used in a professional context but I learned a fair bit and it works quite well.

It's old code — still using google's java-based compiler — so be gentle please :)

There's also a live editor to try it out: http://tjoekbezoer.github.io/jsq/parser.html