Allow subclasses to declare overloads of methods

Suggestion

Allow subclasses to declare an overload of a superclass method:

This would be useful with addEventListener() in order to provide the correct event type for an event name:

class MyElement extends HTMLElement {
  declare addEventListener(type: 'my-event', listener: (this: MyElement, ev: MyEvent) => any, options?: boolean | AddEventListenerOptions): void;
}

🔍 Search Terms

Various combinations: addEventListener subclass declare overload method

A lot of issues were returned from queries, I could have missed something.

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

See above. I'm not sure the reason for not allowing declare on methods currently, so hopefully that could be relaxed.

📃 Motivating Example

See above.

Right now you would have to augment the HTMLElementEventNameMap, but that makes events global, which they might not be if they don't bubble.

💻 Use Cases

See above.

Inizia analizzando come TypeScript gestisce i metodi declare e gli overload dei metodi ereditati. Confronta la dichiarazione addEventListener proposta per la sottoclasse con il comportamento attuale e determina le regole di controllo dei tipi necessarie. La soluzione completata dovrebbe consentire l'overload della sottoclasse senza modificare il JavaScript emesso, preservando al contempo la compatibilità con il metodo della superclasse.