eventservice

A simple Promise-based event bus service.

Installation

npm install eventservice

Usage

Basic usage

import EventService from "eventservice";

// Subscribe to an event named "SomeEventName"
EventService.on("SomeEventName", async () => {
  console.log("Did something!");
});

// Trigger the event
await EventService.fire("SomeEventName");
// -> Did something!

Passing data to a subscriber

import EventService from "eventservice";

// Subscribe to an event named "SomeEventName"
EventService.on("SomeEventName", async (date: Date) => {
  console.log(date);
});

// Trigger the event
await EventService.fire("SomeEventName", new Date());
// -> current date

Getting a result

import EventService from "eventservice";

// Subscribe to an event named "SomeEventName"
EventService.on("SomeEventName", async () => {
  return "Hello World!";
});

// Trigger the event
const result: string | undefined = await EventService.fire<string>("SomeEventName");
console.log(result); // -> Hello World!

Waiting for a nested event

import EventService from "eventservice";

// Subscribe to an event named "SomeEventName2"
EventService.on("SomeEventName2", (name: string) => {
  return new Promise<string>((resolve) => {
    setTimeout(() => resolve(`Hello ${name}!`), 5000);
  });
});

// Subscribe to an event named "SomeEventName1"
EventService.on("SomeEventName1", async (name: string) => {
  return await EventService.fire<string>("SomeEventName2", name);
});

// Trigger the event
const result: string | undefined = await EventService.fire<string>("SomeEventName1", "World");
console.log(result); // after 5s -> Hello World!

Unsubscribing

You can use the off method.

import EventService from "eventservice";

// Subscribe to an event named "SomeEventName"
EventService.on(
  "SomeEventName",
  async (name: string) => {
    return `Hello ${name}!`;
  },
  "SomeKey",
);

// Unsubscribe from the event
EventService.off("SomeEventName", "SomeKey");

// Trigger the event
const result: string | undefined = await EventService.fire<string>("SomeEventName", "World");
console.log(result); // -> undefined

API

EventService.on(eventName, callback, key?)

Subscribes to an event.

• eventName — event name
• callback — async callback that will be called when the event is fired
• key — optional subscription key used for unsubscribing

EventService.off(eventName, key?)

Unsubscribes from an event by key.

EventService.fire(eventName, eventData?)

Fires an event and waits until all subscribers finish.

EventService.clear()

Removes all subscriptions.

Credits

Alexey Ripenko, GitHub

License

MIT