javascript - Passing in Async functions to Node.js Express.js router

Question

This seems like a straightforward google, but I can't seem to find the answer...

Can you pass in ES7 async functions to the Express router?

Example:

var express = require('express');
var app = express();

app.get('/', async function(req, res){
  // some await stuff
  res.send('hello world');
});

If not, can you point me in the right direction on how to handle this problem ES7 style? Or do I just have to use promises?

Thanks!

Answer 1

May be you didn't found results because async/await is an ES7 not ES6 feature, it is available in node >= 7.6.

Your code will work in node. I have tested the following code

var express = require('express');
var app = express();

async function wait (ms) {
  return new Promise((resolve, reject) => {
    setTimeout(resolve, ms)
  });
}

app.get('/', async function(req, res){
  console.log('before wait', new Date());
  await wait(5 * 1000);
  console.log('after wait', new Date())
  res.send('hello world');
});

app.listen(3000, err => console.log(err ? "Error listening" : "Listening"))

And voila

MacJamal:messialltimegoals dev$ node test.js 
Listening undefined
before wait 2017-06-28T22:32:34.829Z
after wait 2017-06-28T22:32:39.852Z
^C

Basicaly you got it, you have to async a function in order to await on a promise inside its code. This is not supported in node LTS v6, so may be use babel to transpile code. Hope this helps.