Inside Out Async

I nerd sniped myself and made this library.

Exports two functions

API

defer()
deferGenerator()

defer

function defer<T>(): Deferred<T>

interface Deferred<T> {
    promise: Promise<T>
    resolve: (value: T) => void
    reject: (error: Error) => void
}

Creates a promise and control functions. The promise is resolved and rejected by the control functions. Like the Promise constructor but inside out.

import { defer } from 'inside-out-async'
import { Trainer } from 'pokemon-trainer'

const pokemonCaught = defer()
const ash = new Trainer()
ash.on('capture', pokemonCaught.resolve)
ash.on('error', pokemonCaught.reject)

const pokemon = await pokemonCaught.promise
console.log(pokemon) // { name: 'Pikachu', temperament: 'surprised' }

deferGenerator

function deferGenerator<T, TReturn, TNext = unknown>(): DeferredGenerator<T, TReturn, TNext>

interface DeferredGenerator<T, TReturn, TNext> {
    generator: AsyncGenerator<T, TReturn, TNext>
    queueValue: (value: T) => void
    error: (err?: any) => void
    queueError: (err?: any) => void
    return: (value?: TReturn) => void
    queueReturn: (value?: TReturn) => void
}

Creates an async generator and control functions. The async generator yields values, errors, and returns based on the control functions.

queueValue queues a value to yielded next
error drops all queued values, puts the generator in a "done" state, and has the current pending or next call to next() throw an error
queueError puts the generator in a "done" state, and has the current pending or next call to next() throw an error
return() drops all queued values, and puts the generator in a "done" state with the passed in value
queueReturn() puts the generator in a "done" state with the passed in value

import { deferGenerator } from 'inside-out-async'

const pokedex = deferGenerator()
pokedex.queueValue({ name: 'Pikachu' })
pokedex.queueValue({ name: 'Bulbasaur' })
pokedex.queueValue({ name: 'Charizard' })
pokedex.queueReturn()

for await (const pokemon of pokedex.generator) {
  console.log(pokemon) // { name: 'Pikachu' }, { name: 'Bulbasaur' }, { name: 'Charizard' }
}