interface IEventKeys {
  click: String;
  touchdown: String;
}
interface IEventKeysMap {
  click: MouseEvent;
  touchdown: Event;
}
class Test {
  on<U extends keyof IEventKeys>(event: U, fn: (e: IEventKeysMap[U]) => void) {
    console.log(event, fn);
  }
}
document.addEventListener("touchdown", (e) => {
  console.log(e);
});
const test = new Test();

enum EventKeys {
  CLICK = "click",
  TOUCHDOWN = "touchdown",
}
test.on(EventKeys.CLICK, (args) => {
  console.log(args);
});
test.on(EventKeys.TOUCHDOWN, (args) => {
  console.log(args);
});