after

Like after, but for the world of promises. Resolve a promise after some number of calls.

This depends on an environment with Proxies.

install

npm i -S @substrate-system/after
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Module Format

This exposes ESM and common JS via package.json exports field.

ESM

import { after } from '@substrate-system/after'
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Common JS

const after = require('@substrate-system/after')
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pre-built JS

This package exposes minified JS files too. Copy them to a location that is accessible to your web server, then link to them in HTML.

copy

cp ./node_modules/@substrate-system/after/dist/index.min.js ./public/after.min.js
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HTML

<script type="module" src="./after.min.js"></script>
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Example

Resolve a promise after three function calls.

The value returned, next, is a function and also a promise. Call it when you want to increment the count.

import { after } from '@substrate-system/after'

const next = after(3)

// 1
setTimeout(() => next(), 10)

// 2
setTimeout(() => next(), 20)

// 3
setTimeout(() => next(), 30)

// 4 -- this does nothing
setTimeout(() => next(), 40)

next.then(() => {
    console.log('30ms later...')
})
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async

const next = after(3)

setTimeout(() => next, 100)
setTimeout(() => next, 200)
setTimeout(() => next, 300)

const time = Number(new Date())

await next  // wait for 3 calls -- 300ms

const afterTime = Number(new Date())
const diff = afterTime - time

console.log(diff >= 300)  // true
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