😪 await-on

really simple error handling with await/async

inspired by await-to-js whose creator Dima Grossman originally blogged about using destructuring array assignment

Overview

This package basically provides 2 main syntaxes to choose from:

const on = require('await-on');

const fetchData = () => new Promise(/*...*/);

const [err, data] = await on(fetchData());
const [err, data] = await fetchData().handle(); //prototype extension

The goal is to avoid the built-in approach using the try/catch block pattern:

try{
	const data = await fetchData();
	res.send(data);
}catch(err) {
	res.send(err);
}

Quick Usage

using on with the function fetchData which returns a Promise that resolve to some result data:

const {on} = require('await-on');
const fetchData = () => new Promise(/*...*/);

async function foo(req,res) {
	const [err, data] = await on(fetchData());
	if(err) res.send(err);
	else res.send(data);
}

using the prototype extension handle on Promise types is a bit cleaner, and its potentially more readable because its also using the same chaining pattern already standard for working with Promises 🌟 :

require('await-on');

async function foo(req,res) {
	const [err, data] = await fetchData().handle();
	!err ? res.send(data) : res.send(err);
}

Type fuzziness

Non-promises will passthrough same as the behavior of the native await

const [err,answer] = await on(42); //not a promise but ok no big deal
console.log(answer) //> 42

Decorator approach

A decorator on.handler is also provided to wrap promise bearing functions with the handling functionalities:

const {handler} = require('await-on');
let fetchData = () => new Promise(/*...*/);
fetchDataAndHandle = handler(fetchData);

async function foo(req,res) {
	const [err, data] = await fetchDataAndHandle();
	!err ? res.send(data) : res.send(err);
}

Promises/A+ compliant support

You never know what kind of promise you'll get from an external dependency. It can be from Bluebird, Babel polyfill or some other library. on should work with any promise object can then, such as the one provided by the popular bluebird package:

const {on} = require('await-on');
const Bluebird = require('bluebird')

const fetchData = () => new Bluebird(/*...*/);
const [err, data] = await on(fetchData());

License

MIT License. See License in the repository.