It lists the free tracks available in Last.fm (expected to run inside webtask.io)

last.fm-free-tracks.js

var jsdom = require("jsdom");
var _     = require("lodash");

var WebCrawler = {};
var Storage    = {};

!function (crawler) {
  var getFreeDownloadableTracks = function(page, finishCallback) {
    jsdom.env({
      url:     "http://www.last.fm/music/+free-music-downloads?page=" + page,
      scripts: ["http://code.jquery.com/jquery.js"],
      done:    crawlPage(page, finishCallback)
    });
  };

  var crawlPage = function(page, finishCallback) {
    return function(err, window) {
      var $           = window.$;
      var totalPages  = +_.trim($('ul.pagination .pages').text()).match(/of (\d+)/)[1];
      var TRs         = $("table.chartlist tbody tr");
      var tracksCount = TRs.length;

      console.log("Fetching %d free musics list in page %d/%d", tracksCount, page, totalPages);

      TRs.each(function() {
        var $el    = $(this);
        var artist = _.trim($('span.chartlist-ellipsis-wrap a:eq(0)', $el).text());
        var track  = _.trim($('span.chartlist-ellipsis-wrap a:eq(1)', $el).text());
        var url    = $('.chartlist-download-button', $el).attr('href');
        if (artist && track && url) { storeTrack(artist, track, url); }
      });

      if (page < totalPages) {
        getFreeDownloadableTracks(page + 1, finishCallback);
      } else {
        finishCallback(crawler);
      }
    }
  };

  var storeTrack = function(artist, track, url) {
    if (!crawler.hasOwnProperty('cachedTracks')) { crawler.cachedTracks= []; }
    crawler.cachedTracks.push([artist, track, url]);
  };

  var fetchTracksData = function(callback) { getFreeDownloadableTracks(1, callback); };

  crawler.fetchTracks = fetchTracksData;
}(WebCrawler);

module.exports = function(ctx, done) {
  WebCrawler.fetchTracks(function(crawler) {
    crawler.cachedTracks.sort(function (a, b) {
      var artistA = a[0].toLowerCase();
      var artistB = b[0].toLowerCase();
      var trackA  = a[1].toLowerCase();
      var trackB  = b[1].toLowerCase();

      if (artistA < artistB) { return -1; }
      if (artistA > artistB) { return 1; }
      if (trackA < trackB) { return -1; }
      if (trackA > trackB) { return 1; }
      return 0;
    });

    done(null, crawler.cachedTracks);
  });
};