Okay, I know, there are other APIs that works for NodeJS and web browsers, but I couldn't find any using TS, so I wrote my own one which is fully modular.
I written basic test files in the tests directory which contains simple-to-understand code in TypeScript, but it's barely any type definitions there, so it looks pretty much like it's pure JavaScript.
npm i coc-api or npm install coc-api
Only axios, which is supported by both NodeJS and browsers.