https://github.com/heapwolf/asde
A low level module for destructuring asynchronous values.
https://github.com/heapwolf/asde
Last synced: about 1 month ago
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A low level module for destructuring asynchronous values.
- Host: GitHub
- URL: https://github.com/heapwolf/asde
- Owner: heapwolf
- Created: 2017-06-18T13:28:19.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2017-06-24T22:51:25.000Z (almost 8 years ago)
- Last Synced: 2025-03-29T19:11:15.274Z (about 2 months ago)
- Language: JavaScript
- Homepage:
- Size: 4.88 KB
- Stars: 50
- Watchers: 3
- Forks: 13
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# SYNOPSIS
A low level module for destructuring asynchronous values.
# MOTIVATION
Use `async/await` on regular callback APIs, return `[error||null, ...values]`.
# DESCRIPTION
`asde` is a low level module that wraps a node-style function call in a promise
so that it can be used with `async/await`. The promise always resolves with an
array of values (error first). The values can then be identified using
a `destructuring assignment`, providing both the error and values in the same
channel without expectation of a try/catch block.
# USAGE
Here are some notes on how async functions work with the await keyword.
### ASYNC
`async` functions help solve `promise hell`. They provide a synchronous-looking
way to receive asynchronous values.
```js
async function main () {
// the await keyword is only available inside async functions.
// async functions are "shallow"! await is not available
// to any nested, non-async functions in the scope.
// an exception in an async function body
// will throw an unhandled promise rejection.
// try/catch blocks can be used to handle rejections.
}
```
### AWAIT
The `await` keyword waits until a promise resolves or rejects.
```js
const b = new Promise((resolve, reject) => {
setTimeout(() => resolve('b'), 16)
})
async function main () {
try {
console.log('a')
console.log(await b)
console.log('c')
} catch (ex) {
console.log(ex)
}
}
main()
```
If you don't catch, the `rejection` will "bubble up" until it finds a promise
that can handle it. If one isn't found, Node.js (and some browsers) provide a
catch-all event called `unhandledRejection` (similar to `uncaughtException`).
# USAGE
`asde` will return a function that takes the same arguments as the original
function, but does not require a `callback`. The new function should be called
with the `await` keyword from within a `async` function.
```js
const asde = require('asde')
const fs = require('fs')
const stat = asde(fs.stat)
async function main () {
const [errStat, value] = await stat('./file')
if (errStat) {
return console.error(errStat)
}
console.log(value)
}
main()
```
# INSTALL
```js
npm install asde
```