@stackpress/libDocs

API reference

EventEmitter

Use EventEmitter when your event names are exact strings and you want ordered async listeners, before/after hooks, and status results instead of fire-and-forget callbacks

EventEmitter

Priority-aware async event emitter built on TaskQueue .

Import

import { EventEmitter } from '@stackpress/lib';

When To Use It

Use EventEmitter when your event names are exact strings and you want ordered async listeners, before/after hooks, and status results instead of fire-and-forget callbacks.

API

Constructor

type Events = {
  'user.created': [string];
  'user.deleted': [string, boolean];
};

const emitter = new EventEmitter<Events>();

Properties

Name Type Notes
after EventHook<M[keyof M]> Runs after each task. Returning false aborts the queue.
before EventHook<M[keyof M]> Runs before each task. Returning false aborts the queue.
event current Event Metadata for the task being executed.
listeners frozen shallow copy Raw listener registry keyed by event name.

Methods

Method Returns Notes
clear(event) this Removes all listeners for one event.
emit(event, ...args) Promise<ResponseStatus> Returns Status.NOT_FOUND , Status.ABORT , or Status.OK .
makeQueue() TaskQueue Overridable queue factory.
match(event) Map<string, EventMatch> Exact-match lookup in the base class.
on(event, action, priority = 0) this Adds a listener. Higher priority runs first.
tasks(event) TaskQueue Materializes the matching listeners into a queue.
unbind(event, action) this Removes one listener function.
use(emitter) this Merges listeners from another emitter.

Example

import { EventEmitter } from '@stackpress/lib';

type Events = {
  saved: [string];
};

const emitter = new EventEmitter<Events>();

emitter.before = async event => {
  console.log('before', event.event);
};

emitter.on('saved', async id => {
  console.log('saved', id);
}, 10);

await emitter.emit('saved', 'abc123');