How to export module asynchronously in nodejs

Question

I cannot export a module that I wrote it myself in an asynchronous way.

const glob = require('glob');

var confFiles;

glob("conf/**/*.conf", function (er, files) {
    confFiles = files;
});

module.exports = new Promise(function(resolve, reject) {
    resolve(confFiles);
});

This is the module itself and I want to access confFiles in other files but the point is that glob is not asynchronous and I'm having trouble finding my way to solve it.

I'm not sure what Lazily reading means, I'm quite new to Nodejs — Shadow4Kill, Feb 02 '19 at 17:01
Lazily means that reading the configuration file only happens when the code calls for it, and not beforehand. — Kraylog, Feb 02 '19 at 17:02

score 1 · Answer 1 · answered Feb 02 '19 at 17:00

1

Resolve when the callback calls back:

module.exports = new Promise(function(resolve, reject) {
  glob("conf/**/*.conf", function (err, files) {
   if(err) reject(err) else resolve(files);
  });
}));

Or a bit shorter:

 const glob = require("glob");
 const { promisify } = require("util");

module.exports = promisify(glob)("conf/**/*.conf");

answered Feb 02 '19 at 17:00

Jonas Wilms

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How should I use it when I require it? It says like this `Promise { }` when I try to use it. – Shadow4Kill Feb 02 '19 at 17:05
@shadow4Kill https://stackoverflow.com/questions/29516390/how-to-access-the-value-of-a-promise – Jonas Wilms Feb 02 '19 at 17:07
I read it before but didn't get my answer. Thanks for your answer btw. – Shadow4Kill Feb 02 '19 at 17:08

nicholaswmin · Accepted Answer · 2019-02-02T17:41:09.590

I'd export a load method instead:

// conf.js
const glob = require('glob')

module.exports.load = () => new Promise((resolve, reject) => {
  glob('conf/**/*.conf', function (err, files) {
    if (err) return reject(err)

    resolve(files)
  })
})

And then in userland:

// index.js
const conf = require('./conf.js')

conf.load()
  .then(files => {
    console.log(files)
  })

Or, you can just use globe.sync instead and avoid dealing with async code entirely:

// conf.js
const glob = require('glob')

module.exports = glob.sync('conf/**/*.conf')

And then in userland:

// index.js
const files = require('./conf.js')
console.log(files)

Just keep in mind that globe.sync is a blocking operation.

How to export module asynchronously in nodejs

2 Answers2