Example of polling a REST API every 1.5 seconds with Observables in NodeJS

index.js

/**
 * Instructions
 *
 * 1. mkdir test
 * 2. cd test
 * 3. npm init
 * 4. accept all defaults is fine
 * 5. npm install @akanass/rx-http-request
 * 6. paste code below into new file index.js
 * 7. update username, password, other variables
 * 8. node index
 */
// import necessary libraries
const Rx = require('rxjs/Rx');
const RxHR = require('@akanass/rx-http-request').RxHR;

// set up api requrest
let uri  = 'http://api.timezonedb.com/v2/get-time-zone';
let qs = {
  key: 'S3UJYQB3HFMI',
  by: 'zone',
  zone: 'America/New_York',
  format: 'json'
};

// create polling source
let source = Rx.Observable.interval(1500).flatMap(() => RxHR.get(uri, {qs: qs}));

// control variable to let us know when to stop polling
let i = 0;

// start poll
let subscription = source.subscribe(
  res => {
    console.log(JSON.parse(res.body).formatted);
    i++;
    if(i > 5) {
      subscription.unsubscribe();
    }
  },
  err => {
    console.log('error: ', err);
  }
);