event-emitters/dist.es5/EventSource.d.ts

event emitters

export declare type Listener<T> = (message: T) => void;
export interface EventSource<T> {
    subscribe(listener: Listener<T>): Listener<T>;
    unsubscribe(listener: Listener<T>): void;
}
export interface EventSourceWithCurrent<T> extends EventSource<T> {
    currentMessage: T;
}