Method on

apps/chart/src/eventEmitter.ts:24–29

(type: EventType, handler: EventListener)

  handlers: EventListener[] = [];

  on(type: EventType, handler: EventListener) {
    if (!this.handlers[type]) {
      this.handlers[type] = [];
    }
    this.handlers[type].push(handler);
  }

  emit(type: EventType, ...args) {
    this.handlers[type]?.forEach((handler) => handler(...args));