Util class for formatting dates in specific timezones (TypeScript)

dateutils.ts

/// <reference path="./node-definitions/moment.d.ts" />
/// <reference path="./node-definitions/timezone-js.d.ts" />

import moment = module("moment")
import tzjs = module("timezone-js")
import fs = module('fs');

export function init() {
    tzjs.timezone.zoneFileBasePath = './tz';
    tzjs.timezone.loadingScheme = tzjs.timezone.loadingSchemes.PRELOAD_ALL;
    tzjs.timezone.transport = function (opts) {
        if (opts.async) {
            if (typeof opts.success !== 'function') return;
            opts.error = opts.error || console.error;
            return fs.readFile(opts.url, 'utf8', function (err, data) {
                return err ? opts.error(err) : opts.success(data);
            });
        }
        return fs.readFileSync(opts.url, 'utf8');
    };

    tzjs.timezone.init({ async: false });
}

export function momentInTimezone(timezoneName: string): moment.Moment {
    var timezone = new tzjs.Date(timezoneName);
    return moment.utc().subtract('minutes', timezone.getTimezoneOffset());
}