The redux-saga module is a plugin for redux that runs generator-based functions in response to redux actions. Redux-saga generator functions are nice because they behave like co: if you
yield a promise, redux-saga will unwrap the promise for you and throw a catchable error if the promise rejects. If you read The 80/20 Guide to ES2015 Generators, a simple saga should look familiar. However, redux-saga intends to keep using generators rather than async/await. In this article, I'll provide a basic example of using redux-saga, explain why redux-saga can't move to async/await, and consider whether you even need redux-saga in the first place.
Promise.prototype.finally() is the most important new feature, but I think async iterators are a close second. In this article, I'll describe what you need to start using async iterators in Node.js. I'll also provide an example of how to use async iterators with Mongoose cursors.
Express is the most popular HTTP server framework for Node.js, but unfortunately it doesn't have good support for async/await. Express doesn't handle errors in async functions. Fastify is an alternative Node.js server framework that enjoys much better support for async/await in addition to better performance. In this article, I'll show you how Fastify works with async/await and show you the corner cases you need to be aware of.
There's a lot of misinformation on how to use async/await with React and Redux. In general, React does not support async/await, but you can make it work with some caveats. In particular,
render() cannot be async, but React suspense may change this. For example, the below minimal example with Node.js 8.9.4, React 16.4.1, and React-DOM 16.4.1 will throw an error.
One great perk of async/await in Node.js is how well it integrates with existing libraries. By now, most popular Node.js libraries support some sort of promise-based API, so they integrate nicely with async/await. You might even have the pleasure of removing a few dependencies from your
package.json if you start using async/await instead of co. In this article, I'll show you how async/await works with mocha tests, express routes and middleware, and mongoose queries and cursors.
Async/await makes it easy to integrate asynchronous behavior with imperative constructs like for loops, if statements, and try/catch blocks. Unfortunately, it doesn't do the same for functional constructs like
Async/await in Node.js opens up a host of powerful design patterns. Tasks that used to take complex libraries or intricate promise chaining can now be done with rudimentary
if statements and
for loops. I already wrote about these kind of design patterns with co, but async/await makes these patterns accessible in vanilla Node.js, no outside libraries required.
Arguably the biggest new feature in Node.js 7.6.0 is that the much awaited async function keyword is now available without a flag. Callback hell and promise hell are now in the past. But, like Uncle Ben always reminded us, with great power comes great responsibility, and async/await gives you a lot of new and exciting ways to shoot yourself in the foot. You still need to handle errors and be aware of the async nature of your code, otherwise you'll inevitably be complaining about "async/await hell" in 6 months.