Unlocking Node.js v7: How async/await Simplifies Asynchronous Code

With Node.js v6 released as v6.9.0 and entering LTS, Node.js v7 is approaching.

A few days ago, Node.js v7 released its first RC version, whose most notable feature is support for the async/await keywords, thanks to the V8 engine v5.4. To use these keywords, you can enable the feature via a command‑line flag: node --harmony-async-await What does async/await mean? In short:

async/await lets developers write code in a synchronous style while it actually runs asynchronously.

Essentially, async/await is a syntactic wrapper around Promises. For example, calling a function that returns a Promise, such as fetch, to asynchronously retrieve a resource:

const fun = function(url) {
  return fetch(url).then(function(res) {
    // prints 200
    console.log(res.status);
  })
};

fun('https://s.taobao.com');

If you write it with async/await:

const fun = async function(url) {
  const res = await fetch(url);
  // prints 200
  console.log(res.status);
};

fun('https://s.taobao.com');

In more complex real‑world usage, async/await is simpler and more direct than using Promises.

Want to try it? You can download the RC packages from https://nodejs.org/download/rc/v7.0.0-rc.1/, but a more convenient method is to use nvm:

NVM_NODEJS_ORG_MIRROR=https://nodejs.org/download/rc nvm install 7

After the official release, you can simply run nvm install 7 to install it.

As a curious and diligent programmer, why not read the original article to learn more about async/await?