A package for filtering Node.js events. Your listeners only get executed when the specified predicate is satisfied.
import { EventEmitter } from 'event'
import 'event-filter'
const event = new EventEmitter()
event.onWhen('someEvent', (...) => /* predicate */, (...) => /* normal listener */)
event.onceWhen('someEvent', (...) => /* predicate */, (...) => /* normal listener */)event-filter adds the following methods to the EventEmitter prototype:
| Method Name | Description |
|---|---|
onWhen (event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): this |
Subscribe to the specified event, but only call the listener when the predicate is satisfied. |
onceWhen (event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): this |
Subscribe to the specified event, calling the listener the first time the predicate is satisfied. |
event-filter also exports the following methods:
| Method Name | Description |
|---|---|
onWhen<TEvent extends EventLike> (evt: EventLike, event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): TEvent |
Subscribe to the specified event, but only call the listener when the predicate is satisfied. |
onceWhen<TEvent extends EventLike> (evt: EventLike, event: string | symbol, predicate: (...args: any[]) => boolean, listener: (...args: any[]) => void): TEvent |
Subscribe to the specified event, calling the listener the first time the predicate is satisfied. |
Using these allows you to call onWhen and onceWhen on objects that are like EventEmitter, but don't actually extend the superclass.
event-filter contains defines TypeScript definitions for type safety.
event-filter adds JSDoc comments to both new methods.
To build, install all devDependencies and execute npm run build.
To build with a watch, execute npm run watch:build.
To test, install all devDependencies and execute npm run test.