If I wanted to learn to write browser-based games what would be a good place to start? I know some JavaScript but am not particularly enamoured with the language. Should I learn TypeScript plus some framework? (React?) Or how about something functional like Elm?
Frameworks aren't very relevant for games. I'd go with Typescript (because it will tell you about some errors earlier and provide code completion support if properly set up) and WebGL. Then do everything in the canvas and essentially ignore the fact that you have a browser with a DOM etc.
An option is to target WASM and write the game in Rust or C++, using Emscripten WebGL bindings. This is harder but allows you to write high performance games that would run too slow in Javascript.