People often promote this but there’s a huge gap between script tag to include jquerg.min (for example) and requiring the entire node/npm ecosystem to cross compile etc everything else (provided you weren’t already). This is a high tax to pay.
Typescript is super easy to bring into a project. Just rename .js to .ts and turn the validations off. Any valid JS is also valid TS. Build step is one command to run tsc. You can turn things on slowly as you refactor into idiomatic typescript.
React is a PITA to setup and learn, as is Angular. They're the modern equivalent of Java EE. "Heavy" but if you have something complex to do and know your way around they make hard things easy. The learning curve is tough but so worth it
