Arguably the biggest gap in Express' API is its

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.

ES2018 introduces several new JavaScript language features that are great for Node.js developers. 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.

Async/await is the most important new feature in JavaScript in recent memory. Generators provided an alternative in ES6, but generators required outside libraries and provided more flexibility than most developers needed. When I was a guest on the JavaScript Air podcast, the host Kent C. Dodds asked me what generators could do that async/await couldn't, and my answer was essentially "nothing that the vast majority of developers would care about."

Async/await is the big new feature in the 2017 edition of the JavaScript language spec. However, async/await has a lot in common with generators, a new feature from the 2015 JavaScript language spec. There's plenty of questions on StackOverflow about what makes async/await different, and with good reason. If you use co, your generator-based code looks a lot like async/await.

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 forEach, map, reduce, and filter. Using these constructs with async functions leads to behavior that can seem downright baffling. In this article, I'll show you some common gotchas for async functions with JavaScript's built-in functional array methods and how to work around them.

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.

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