Wiki says: TypeScript is an open-source programming language developed and maintained by Microsoft. It is a strict syntactical superset of JavaScript, and adds optional static typing to the language.
TypeScript is designed for development of large applications and transcompiles to JavaScript.[5] As TypeScript is a superset of JavaScript, existing JavaScript programs are also valid TypeScript programs. TypeScript may be used to develop JavaScript applications for both client-side and server-side execution (as with Node.js or Deno).
For several years I am using app, which advertises for me products on Fler automatically. First, I made an Opera extension, later I switched from Opera to Chrome and with that also ported the extension to Chrome. But web technologies evolved a lot and my extension is not working properly anymore. Fixing it seems to be too difficult.