Javascript: Promise.all doesn't seem to be resolving

Question

I'm trying to map over some RSS feeds using feedparser-promised, but my call to Promise.all() isn't returning anything. (use of var is from my REPL, which doesn't support const or let)

var feedparser = require('feedparser-promised');
var R = require('ramda');
var URLS = ['http://feeds.gawker.com/gizmodo/full',
            'http://kotaku.com/vip.xml',
           'http://www.medievalhistories.com/feed/'];

var getAllFeeds = (urls) => {
    promises = R.map(feedparser.parse, urls);
    Promise.all(promises)
        .then((itemArrs) => itemArrs)
        .catch((err) => {throw new Error(err)});
}

var x = getAllFeeds(URLS);
console.log(x);

x comes back as undefined. If I do a log on promises, it shows as an array of Promises, as expected. What am I missing?

Even if I replace the `.then` with `.then((itemArrs) => console.log(itemArrs))`, the itemArrs never get logged — Kevin Whitaker, Nov 10 '15 at 13:54

joews · Accepted Answer · 2015-11-10T14:14:54.493

1

x is undefined because getAllFeeds is a arrow function with statement body that does not explicitly return.

You should return the Promise.all promise and consume the results in then/catch handlers:

var getAllFeeds = (urls) => {
    var promises = R.map(feedparser.parse, urls);
    return Promise.all(promises)
}

getAllFeeds(URLS)
  .then(items => {
    console.log(items);
  })
  .catch(err => {
    console.error(err);
  })

edited Nov 10 '15 at 14:14

answered Nov 10 '15 at 14:08

joews

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Still looks like I'm missing something; nothing ends up logging out. – Kevin Whitaker Nov 10 '15 at 14:12
@KevinWhitaker: Maybe you're got a rejection – Bergi Nov 10 '15 at 14:14
Looks like my REPL was acting up. @joews answer works – Kevin Whitaker Nov 10 '15 at 14:17

Javascript: Promise.all doesn't seem to be resolving

1 Answers1