hassanzohdy/mongez-events/bus

events.subscribe(event: string, callback: Function): EventSubscription
events.on(event, callback): EventSubscription            // alias
events.addEventListener(event, callback): EventSubscription  // alias

type EventSubscription = {
  callback: Function;
  event: string;
  dispatch(...args: any[]): any;        // call the callback directly
  unsubscribe(): void;
};

events.trigger(event: string, ...args: any[]): any
events.emit(event, ...args): any                   // alias

events.subscribe("save.before", (data) => {
  if (!isValid(data)) return false;     // vetoes the save
});
const ok = events.trigger("save.before", payload);
if (ok === false) return;

events.triggerAll(event: string, ...args: any[]): EventTriggerResponse
type EventTriggerResponse = {
  event: string;
  length: number;       // number of callbacks invoked
  results: any[];       // all non-undefined return values
};

events.triggerAsync(event, ...args): Promise<any>
events.triggerAllAsync(event, ...args): Promise<EventTriggerResponse>

await Promise.all(
  events.subscriptions("flush").map(s => s.dispatch(data)),
);

events.subscriptions(event: string): EventSubscription[]
events.unsubscribe(event?: string): this    // detach one event or all
events.off(event?: string): this            // alias

const sub = events.subscribe("ping", (n) => n * 2);
sub.dispatch(21);   // 42