README

To-await

To-await is an efficient and clean way to write Asynchronous code as Synchronous code.

It it based on this article - How to write async await without try-catch blocks in Javascript it also has the only addition that we support Promise.All.

I have been using this technique for more than a year in production. It is a pretty simple approach to avoid callback hell and promise chains. Furthermore, I found my self nesting try and catch. These are the primary cases where this package alleviates issues.

Installation

npm install to-await

This assume that you are using npm as package manager.

The Gist

ES6 modules

import { to, toAll } from 'to-await';

CommonJS

const { to, toAll } = require('to-await');

Promise Example

import { to, toAll } from 'to-await'

const firstPassTest = async () => {
    try {
        let [error, result] = await to(return10());
        console.log(`error: ${error}, result: ${result}`);

        [error, result] = await to(delay(3000));
        console.log(`error: ${error}, result: ${result}`);
        [error] = await to(rejected());
        console.log(`error2: ${error}`);
        if (error) {
            throw error;
        }
    } catch (err) {
        console.error(err);
    }
};

firstPassTest();

Array of Promisses

const { to, toAll } = require('to-await');

const secondTest = async () => {

    const arrayOfPromises = array => array.map(async (el, index) => 1 + index);
    const promises = arrayOfPromises([1, 2, 3, 4, 5, 6, 7]);
    let [error, data] = await toAll(promises);
    console.log(`error: ${error}, data: ${data}`);
}

secondTest();

Where it might help you

In this case below, if you want to use a try catch to wrap you function, you are not able to throw an error inside of the callback/Promise since you are inside of another scope. This is an example from nodejs docs.

const fs = require('fs');
const { promifisy } = require('util');

const writeAsync = promisify(fs.writeFile);
const data = new Uint8Array(Buffer.from('Hello Node.js'));

function foo() {
    try {
        fs.writeFile('message.txt', data, (err) => {
            // this throw will not be catch by the throw
            // because you are inside the callback
            if (err) throw err;
            console.log('The file has been saved!');
        });
    } catch (err) {
        console.error(err);
    }
}

async function fooNicer() {
    try {
        const [error] = await to(writeAsync('message.txt', data, ));
        if (error) {
            throw error;
        }
        console.log('The file has been saved!');
    } catch (err)
}

Usage no npm install needed!