From Age of Empires 4 Modding

By default Scar / Lua is used for Age of Empires 4 scripting. The TypeScriptToLua (TSTL) project can convert TypeScript to Lua.

TypeScript mod example / template which can be used as a starting point: https://github.com/aoemods/aoe4-typescript-template

Types repository which the above template uses: https://github.com/aoemods/aoetypes

Project using TypeScript for scenario scripts: https://github.com/aoemods/dodge-mod