0.0.1 • Published 7 years ago
typed-event-emitter-2 v0.0.1
typed-event-emitter-2
This module provides a strict usage and implementation of Node.js' EventEmitter API. Without needing to rely on another implementation. Arbitrary events or listeners can not be added without a TypeScript compile time error.
Install
$ npm i typed-event-emitter-2
Usage
Before using Node.js / Browsers conventional EventEmitter
.
import * as UntypedEventEmitter from 'events';
const conventionalEventEmitter = new UntypedEventEmitter();
conventionalEventEmitter
.on('foo', (arg: number) => console.log(Math.abs(arg)))
.on('bar', (arg: string) => console.log(arg.length))
.on('baz', () => console.log('baz'));
conventionalEventEmitter.emit('foo', 1);
conventionalEventEmitter.emit('foo'); // Should have an error
conventionalEventEmitter.emit('bar', 'bar');
conventionalEventEmitter.emit('bar', 1); // Should have an error
conventionalEventEmitter.emit('baz');
conventionalEventEmitter.emit('baz', 'bar'); // Should have an error
Using a type safe EventEmitter with no arguments in listeners.
import TypedEventEmitter from 'typed-event-emitter-2';
const typedEventEmitterNoArgs = new TypedEventEmitter<'foo' | 'baz'>();
typedEventEmitterNoArgs
.on('foo', () => console.log('foo'))
.on('baz', () => console.log('baz'));
typedEventEmitterNoArgs.emit('baz');
typedEventEmitterNoArgs.emit('foo');
Using a type safe EventEmitter with one argument in listeners.
import TypedEventEmitter from 'typed-event-emitter-2';
class TypedEventEmitterOneArg extends TypedEventEmitter<never, {
foo: number
bar: string
}> {}
const typedEventEmitterOneArg = new TypedEventEmitterOneArg();
typedEventEmitterOneArg
.on('foo', (arg: number) => console.log(Math.abs(arg)))
.on('bar', (arg: string) => console.log(arg.length));
typedEventEmitterOneArg.emit('foo', 1);
typedEventEmitterOneArg.emit('bar', 'bar');
Using a type safe EventEmitter with zero or one arguments in listeners.
import TypedEventEmitter from 'typed-event-emitter-2';
enum keys {
baz,
zoo,
};
const typedEventEmitterMix = new TypedEventEmitter<
keyof typeof keys,
{
foo: number
bar: string
}
>();
typedEventEmitterMix
.on('foo', (arg: number) => console.log(Math.abs(arg)))
.on('bar', (arg: string) => console.log(arg.length))
.on('baz', () => console.log('baz'));
typedEventEmitterMix.emit('foo', 1);
typedEventEmitterMix.emit('bar', 'bar');
typedEventEmitterMix.emit('zoo');
License
typed-event-emitter-2
is licensed under the ISC License.
0.0.1
7 years ago