Discord.JS self-bot code that fetches the message counts for each user in a guild. (originally written September 7, 2017, revised slightly today)

DiscordGuildMessageCounter.js

/**
 * @file Defines a function used to count the messages of every user in a Discord guild.
 * @author wooningc
 * @requires discord.js.org
 */
"use strict";

/**
 * @function countMessages
 * @param {Guild} guild The guild whose members will be iterated through.
 * @param {Object} [options] List of customizable options.
 * @param {boolean} [options.debug] Whether or not to print progress/errors to the console.
 * @param {number} [options.timeoutThreshold=30000] If this number of milliseconds has passed since the last fetched member, then resolve. Use 0 or any number lower for no timeout.
 * @param {function} [options.onusercomplete] (event) The function to be called when a user's message count has been logged.
 * @returns {Promise<Object[]>} Array of objects with pairs of User objects and their respective message counts, sorted by message count in descending order.
 * @desc Takes a guild and returns a sorted list of all its members and their message counts.
 */
function countMessages(guild, options={}) {
    return new Promise(function (resolve, reject) {
        var members;
        var size;
        var date;
        var interval;
        
        var counts = [];

        var log = options.debug ? console.log : () => undefined;
        
        if (isNaN(options.timeoutThreshold)) options.timeoutThreshold = 30000;
        if (typeof options.onusercomplete !== "function") options.onusercomplete = () => undefined;

        if (guild.large) guild.fetchMembers().then(initialize);
        else initialize();

        function initialize() {
            members = guild.members;
            size = members.size;
            date = Date.now();
            if (options.timeoutThreshold > 0) {
                interval = setInterval(function () {
                    if (Date.now() - date > options.timeoutThreshold) {
                        log(`Timed out when counting ${guild.name}`);
                        sort();
                    }
                }, 1000);
            }
            iterate();
        }

        function iterate() {
            members.forEach(function (member) {
                var user = member.user;
                    
                guild.search({
                    author: user
                }).then(
                    results => { increment(user, results); },
                    error   => { console.log(error); }
                ).catch(
                    error   => { console.log(error); }
                );
            });
        }

        function increment(user, results) {
            date = new Date();
            counts.push({ amount: results.totalResults, user });
            log(`${guild.name}: ${counts.length} out of ${size} complete (${user.tag})`);
            if (options.onusercomplete) options.onusercomplete({ user, results, i: counts.length, size });
            if (counts.length >= size) sort();
        }

        function sort() {
            clearInterval(interval);
            counts.sort((a, b) => b.amount - a.amount);
            log(`Finished counting messages in ${guild.name}`);
            resolve(counts);
        }
    });
}