Function within a loop

Question

I'm trying to write a script for hubot to get player statistics for a game, however I am having some trouble with list comprehension.

Here's my code

listings = []
listings = 
  (for player in players
    request "http://pwa.wp3.pl/curvefever/?player=" + player , (err, res, body)->
      $ = cheerio.load(body)
      msg.send "Hello, world!1"
      {name: $('b').slice(0).eq(0).text().toLowerCase(), rank: parseInt($('td').slice(37).eq(0).text(),10)})

msg.send "Hello, world!2"
for player of listings
  msg.send "Hello, world!3"
  msg.send player.name + " " + player.rank

when running this I get "Hello, world!2" followed by several "Hello, world!1" and no "Hello, world!3" as listings is (presumably) empty.

The script works when I do msg.send instead of trying to capture the listings in an array, however I'd like to sort the listings based on rank too.

Answer 1

Several things are going in here.

First, you do not need to initialize listings as an array first.

Second, I think you're looking for for player in listings.

Third, and I think that's the most important point : request sends an ajax request. Ajax requests are, by definition, asynchronous.

So what you actually push into your array is the result of "request" : probably nothing.

I'd recommend using a library such as async.js, a promise implementation, etc, or just a i = players.length that you decrement and check each time a request succeeds, to ensure your code awaits all results before it executes.