EventBus Types

types.ts

/** 
 * type for generic Event-Handler callbacks 
 */
export type EventHandler<T = any> = (data: T) => void;

/** 
 * validate each Event Types callback parameters 
 */
export type EventContract<T> = { [K in keyof T]: T[K] }

/** 
 * An EventBus interface with typed events and callbacks 
 */
export interface EventBus<T extends EventContract<T>> {

   /** 
    * register a callback for specific named event 
    */
   when<K extends keyof T>(event: K, id: string, handler: EventHandler<T[K]>): void,

   /** 
    * fire a specific named event with an appropriate payload 
    */
   send<K extends keyof T>(event: K, id: string, args: T[K]): void
}