Useful reading to understand the Promises, Generators and the async/await feature for Node.js/JavaScript

By: ( +David Herron; Date: 2016-11-20 17:01

Tags: Node.JS »»»» Asynchronous Programming

The long-awaited async/await feature for JavaScript promises to make our lives much easier. Instead of asynchronous JavaScript programming being tricky and error-prone, with async/await our code will look like regular synchronous code we write in other languages, but will accommodate asynchronous code execution while retaining the single-threaded nature of JavaScript. With this feature we declare async functions, and within their boundary magic occurs - we can put the "await" keyword in front of a function which produces a Promise, and automagically JavaScript will wait for the Promise to resolve and give us the result or else throw the error. What follows is a list of posts describing how to use async/await.

Also included are links to posts about Promises and Generators. Together the three give us a rich tapestry of capabilities to simplify asynchronous programming, make our code look cleaner and more robust.

( Write Modern Asynchronous Javascript using Promises, Generators, and Coroutines Shows several ways to use Generators in an Express application. He suggests that since co(function* () { }) is so similar to async functions, and much more widely available, that we should start using those today.

( Tips for using async functions (ES2017) An excellent tour of best practices for using async functions.

( ES proposal: asynchronous iteration A proposal (don't get too excited yet) for asynchronous looping structures.

( Three useful Babel presets Lists several useful Babel tools to enable certain experimental features in JavaScript, including the async/await feature.

( promise-sequential "Like Promise.all, but sequentially"

( JavaScript Promise API An excellent tour of the Promise object and the best practices for its use.

( Understanding JavaScript Promises, Pt. I: Background & Basics A good introduction to Promise's.

( Using ES6 array destructing with Promises

( The Hidden Power of ES6 Generators: Observable Async Flow Control An in-depth look at Generator functions.

( Retrofitting Node/NPM Packages with Async/Await. Rewriting your code to use async/await

( Error handling in long Promise chains "The longer the chain the easier it is to break it"

( Promises, Promises (or how not to lose your marbles) Some best practices for using Promise's.

( Understanding JavaScript’s async await

( Installing Babel V6.x ES7 Async/Await on Node.js v6.2.0 with Nodemon A Stack Overflow question about using Babel to transpile async/await

( Using ES7 Async/Await in Node.js & Babel.js

( Get the value of a Javascript Promise in a synchronous way An excellent discussion of why we need async/await to simplify asynchronous programming in JavaScript

( ES7 Async/Await in Node.js with Babel.js

( - Home page for the committee developing async/await for JavaScript

( Node.js Tip - Minimal Babel with Node v6 The precise minimum steps required to setup Babel with Node.js 6.12 to use async/await.