app.ts

import express, { Request, Response, NextFunction } from 'express';
import split = require('@splitsoftware/splitio');

interface LocationWithTimezone {
  location: string;
  timezoneName: string;
  timezoneAbbr: string;
  utcOffset: number;
};

const app = express();
const port = 3000;

app.listen(port, () => {
  console.log(`Timezones by location application is running on port ${port}.`);
});

const factory: SplitIO.ISDK = split.SplitFactory({
  core: {
    authorizationKey: '7m4qctr1k6vi9kshbbu972vqm8nklom6qnjh'
  }
});

const client: SplitIO.IClient = factory.client();

const getLocationsWithTimezones = (request: Request, response: Response, next: NextFunction) => {
  let locations: LocationWithTimezone[] = [
    {
      location: 'Germany',
      timezoneName: 'Central European Time',
      timezoneAbbr: 'CET',
      utcOffset: 1
    },
    {
      location: 'China',
      timezoneName: 'China Standard Time',
      timezoneAbbr: 'CST',
      utcOffset: 8
    },
    {
      location: 'Argentina',
      timezoneName: 'Argentina Time',
      timezoneAbbr: 'ART',
      utcOffset: -3
    },
    {
      location: 'Japan',
      timezoneName: 'Japan Standard Time',
      timezoneAbbr: 'JST',
      utcOffset: 9
    }
  ];

  if (request.treatment == 'on')
    locations.push({
      location: 'Kenya',
      timezoneName: 'Eastern Africa Time',
      timezoneAbbr: 'EAT',
      utcOffset: 3
    });

  response.status(200).json(locations);
};

const getTreatmentMiddleware = function (request: Request, response: Response, next: NextFunction) {
  const key: SplitIO.SplitKey = <SplitIO.SplitKey>request.headers['authorization'];
  request.treatment = client.getTreatment(key, 'timezone_split');
  next();
};

app.get('/timezones', getTreatmentMiddleware, getLocationsWithTimezones);