event-promisify

• event-promisify
• Documentation
  • Errors
  • Multiple emitted values
  • Examples
    • Simple promisification
    • Event filtering
    • Event aggregation
    • Custom termination event
    • Ignore errors

event-promisify

Just run npm install event-promisify

Documentation

This implementation supports basic promisification, event filtering, aggregation, custom specification of error events and is promise library agnostic (defaults to native/global Promise object).

Errors

Keep in mind that some promise implementations do not take kindly to using non-errors for rejections. Therefor when a(an) (custom) error event, the event value will be contained in an error object, but only if the event is not an error already. If the emitted object is a string however, the string will be used for the errors message, no event property will be added!

Multiple emitted values

Not supported, multiple emitted values is usually a sign of bad design. If you happen to find a good reason why this should be supported, please create an issue. Meanwhile this will suffice.

function fixMultiArgEventEmitter(emitter, name, newName) {
	emitter.on(name, function() { emitter.emit(newName, Array.prototype.slice.call(arguments)));
}

Examples

Simple promisification

const promisifyEvent = require('event-promisify')(YOUR_PROMISE_CONSTRUCTOR_HERE);

promisifyEvent(someEventEmitter, 'someEvent')
.then(...)

Event filtering

promisifyEvent(someEventEmitter, {
	name: 'someEventThatOccursmultipleTimes',
	filter: event => someConditionThatReturnsABooleanWhenYouAreDone(event)
})
.then(...)

Event aggregation

promisifyEvent(someEventEmitter, {
	name: 'end',
	aggregate: 'data'
})
.then(result => console.log( /* array of aggregated event data */ result.aggregated, /* final event data */ result.value))

Custom termination event

promisifyEvent(someEventEmitter, {
	name: 'end',
	errorName: 'disconnect'
})
.catch(error => ...)

Ignore errors

Custom errors will still be handled.

It usually means you did something wrong if this happens, but some libraries may emit intermediate errors when they actually should emit warnings or similar.

Be also warned that this MAY lead to promises not settling!

promisifyEvent(someEventEmitter, {
	name: 'end',
	ignoreErrors: true
})
.then(...)

For now more info check test.js and the index.js for further information.