我应该在等待事件发生时明确地创建一个承诺吗？

Question

I am writing a function to get an rss feed and return the date of the last update:

var FeedParser = require('feedparser'),
Promise = require('bluebird'),
request = require('request');

function getDate() {
    var deferred = Promise.defer();
    var feed = new FeedParser();
    request('rss.xml');
    .on('response',function() {
        this.pipe(feed);
    });

    feed.on('meta',function() {
        deferred.resolve(this.meta.date);
    });

    return deferred.promise;
}

Is this an anti-pattern? What is the proper way to do this?

Answer 1

You can simplify it a bit.

var FeedParser = require('feedparser'),
Promise = require('bluebird'),
request = require('request');

function getDate() {
  return new Promise(function(resolve, reject){
    var feed = new FeedParser();
    request('rss.xml').on('error', reject).pipe(feed);
    feed.on('meta',function() {
      resolve(this.meta.date);
    }).on('error', reject);
  });
}