Repack Moment.js data, limited to a subset of zones

build-momentjs-data.js

import gulp from 'gulp';
import moment from 'moment-timezone/moment-timezone';
import 'moment-timezone/moment-timezone-utils';
import fs from 'fs';
import config from '../../config';

const inputFile = 'node_modules/moment-timezone/data/unpacked/latest.json';
const outputFile = 'app/lib/moment-timezone-data.json';
const start = 2014;
const end = moment().add(5, 'years').year();

function buildMomentData(callback) {
    const momentData = JSON.parse(fs.readFileSync(inputFile).toString());
    const requiredTimeZones = [].concat(config.get('requiredTimeZones'), ['Zulu', 'UTC']);
    const trimmedMomentData = Object.assign({}, momentData);
    trimmedMomentData.zones = [];

    requiredTimeZones.forEach(zone => {
        const zoneData = momentData.zones.find(momentZone => momentZone.name === zone);
        const trimmedZoneData = moment.tz.filterYears(zoneData, start, end);
        trimmedMomentData.zones.push(trimmedZoneData);
    });

    trimmedMomentData.zones = trimmedMomentData.zones.map(zoneData => moment.tz.pack(zoneData));

    fs.writeFile(outputFile, JSON.stringify(trimmedMomentData));
    callback();
}

gulp.task('moment', function (callback) {
    buildMomentData(callback);
});

moment-proxy.js

import moment from '../../node_modules/moment-timezone/moment-timezone';
moment.tz.load(require('./moment-timezone-data.json'));

export default moment;