Langium is an open source language engineering tool with first-class support for the Language Server Protocol, written in TypeScript and running in Node.js.
Parser Building Toolkit for JavaScript.
Chevrotain is a blazing fast and feature rich Parser Building Toolkit for JavaScript with built-in support for LL(K). Grammars and 3rd party plugin for LL(*) grammars. It can be used to build parsers/compilers/interpreters for various use cases ranging from simple configuration files, to full-fledged programing languages.
Spell, Style, and Grammar Checker for WordPress, Firefox, TinyMCE, jQuery, and CKEditor