Dfyjkt

I am trying to extend an existing interface to add additional event handlers. The interface I am extending already has several event handlers defined.

Here is the base interface:

export interface Emitter 

 on(event: 'connect', listener: (err: Error) => void ):this;

 on(event: 'end', listener: () => void ):this;

Here is also the base class:

export class Emitter extends events.EventEmitter 

Here is my interface:

export interface EmitterExtended extends Emitter 
 on(event: 'status', listener: (status: ConnectionStatus) => void ):this;
 status?: ConnectionStatus;

And here is the error typescript gives:

Interface 'EmitterExtended' incorrectly extends interface 'Emitter'.
Types of property 'on' are incompatible.

Found the solution here

By declaring a module with the same name as the imported module, you can augment existing declarations

import Observable from "./observable";
declare module "./observable" 
 interface Observable<T> 
 map<U>(f: (x: T) => U): Observable<U>;
 


Observable.prototype.map = function (f) 
 // ... another exercise for the reader