tsee

tsee

Typed EventEmitter implemented with tsargs, based on nodejs EventEmitter.
Fully implements NodeJS.EventEmitter type, provides interface & proxy class.

Install & use

npm i tsee

Simple usage:

import { EventEmitter } from 'tsee';

const events = new EventEmitter<{
    foo: (a: number, b: string) => void,
}>();

// foo's arguments is fully type checked
events.emit('foo', 123, 'hello world');

Cast any other compatible to NodeJS.EventEmitter to typed:

import { asTypedEventEmitter } from 'tsee';

const typedEmitter = asTypedEventEmitter<{
    foo: (a: number, b: string) => void,
    boo: (a: number, b: string) => void,
}>(myEmitter);

typedEmitter.emit('foo', 123, 'hello world');

Advenced usage for non default event emitters

If you use custom EventEmitter implementation, you can simply cast it to tsee.IEventEmitter interface:

import { CustomEventEmitter } from 'my-event-emitter';
import * as tsee from 'tsee';

// Simple type case
const typed = new CustomEventEmitter() as any as tsee.IEventEmitter<{ ... }>;

// Functional cast with `NodeJS.EventEmitter` type constraints
const typed = asTypedEventEmitter<{ ... }>(new CustomEventEmitter());

tsee.EventEmitter class is implemented EventEmitter from 'events' package.

Api

EventEmitter<T> where T extends { [eventName]: Call signature }.

EventEmitter.emit's args is fully typed based on events map.

For foo event in example above, signature is: emit(eventName: 'foo', a: number, b: string).