getFollowers.js

var beam = {
  "channelID": 38756,
  "getFollowers": function(limit) {
    return $.getJSON("https://beam.pro/api/v1/channels/" + beam.channelID).promise()
      .then(function(channelData) {
        return (function getFollowers(numFollowers, count, followers, page) {
          var limit = Math.min(count, 100);
          if (page == null) page = Math.floor(numFollowers / limit);
          return $.getJSON("https://beam.pro/api/v1/channels/" + beam.channelID +
                            "/follow?page=" + page + "&limit=" + limit + "&fields=username").promise()
            .then(function(followerData) {
              for (var i = followerData.length - 1; i >= 0; i--)
                if (followers.push(followerData[i].username) >= count) return followers;
              if (--page < 0) return followers;
              return getFollowers(numFollowers, count, followers, page);
            });
        }(channelData.numFollowers, limit, [ ]));
      });
  }
};