achingbrain
race-event
Race an event against an AbortSignal
About
Race an event against an AbortSignal, taking care to remove any event listeners that were added.
Example - Getting started
import { raceEvent } from 'race-event'
const controller = new AbortController()
const emitter = new EventTarget()
setTimeout(() => {
controller.abort()
}, 500)
setTimeout(() => {
// too late
emitter.dispatchEvent(new CustomEvent('event'))
}, 1000)
// throws an AbortError
const resolve = await raceEvent(emitter, 'event', controller.signal)Example - Aborting the promise with an error event
import { raceEvent } from 'race-event'
const emitter = new EventTarget()
setTimeout(() => {
emitter.dispatchEvent(new CustomEvent('failure', {
detail: new Error('Oh no!')
}))
}, 1000)
// throws 'Oh no!' error
const resolve = await raceEvent(emitter, 'success', AbortSignal.timeout(5000), {
errorEvent: 'failure'
})Example - Customising the thrown AbortError
The error message and .code property of the thrown AbortError can be
specified by passing options:
import { raceEvent } from 'race-event'
const controller = new AbortController()
const emitter = new EventTarget()
setTimeout(() => {
controller.abort()
}, 500)
// throws a Error: Oh no!
const resolve = await raceEvent(emitter, 'event', controller.signal, {
errorMessage: 'Oh no!',
errorCode: 'ERR_OH_NO'
})Example - Only resolving on specific events
Where multiple events with the same type are emitted, a filter function can
be passed to only resolve on one of them:
import { raceEvent } from 'race-event'
const controller = new AbortController()
const emitter = new EventTarget()
// throws a Error: Oh no!
const resolve = await raceEvent(emitter, 'event', controller.signal, {
filter: (evt: Event) => {
return evt.detail.foo === 'bar'
}
})Example - Terminating early by throwing from the filter
You can cause listening for the event to cease and all event listeners to be removed by throwing from the filter:
import { raceEvent } from 'race-event'
const controller = new AbortController()
const emitter = new EventTarget()
// throws Error: Cannot continue
const resolve = await raceEvent(emitter, 'event', controller.signal, {
filter: (evt) => {
if (...reasons) {
throw new Error('Cannot continue')
}
return true
}
})Install
$ npm i race-eventBrowser <script> tag
Loading this module through a script tag will make it's exports available as RaceEvent in the global namespace.
<script src="https://unpkg.com/race-event/dist/index.min.js"></script>API Docs
License
Licensed under either of
- Apache 2.0, (LICENSE-APACHE / http://www.apache.org/licenses/LICENSE-2.0)
- MIT (LICENSE-MIT / http://opensource.org/licenses/MIT)
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.