What if your clock was off? Get the time from other servers date headers

tell_the_time.js

var http = require('http'),
    fs = require('fs'),
    loadDomains, getTheTimeFromServerList, formatDateHeader;

loadDomains = new Promise(function (resolve, reject) {
    var servers;
    fs.readFile('hostnames.txt', 'utf8', function (err, data) {
        if (err) {
            reject('Unable to read hostnames.txt');
        }
        servers = data
            .trim()
            .split('\n')
            .map(function (r) {
                return r.trim();
            });
        resolve(servers);
    });
});
formatDateHeader = function (date) {
    return new Date(date).toISOString();
};
getTheTimeFromServerList = function (servers) {
    return new Promise(function (resolve) {
        var i;
        for (i = 0; i < servers.length; i += 1) {
            (function (server) {
                http.get('http://' + server + '/', function (resp) {
                    if (resp.headers.date) {
                        return resolve(formatDateHeader(resp.headers.date));
                    }
                }).on('error', function () {
                    return;
                });
            })(servers[i]);
        }
    });
};

loadDomains.then(getTheTimeFromServerList).then(console.log).catch(console.log);