rxjs-online-offline-composed.js

const { Observable } = require('rxjs/Observable');
require('rxjs/add/operator/filter');
require('rxjs/add/operator/switchMap');
require('rxjs/add/operator/take');
require('rxjs/add/operator/toPromise');
const axios = require('axios');

const online$ = createOnline$();

//only make the network request when we're online
//the request will simply get queued up until then 
function requestWhenOnline(ajaxPromiseFn) {
  return online$
    .filter(online => online)
    //we only reach this point when we're online
    .switchMap(ajaxPromiseFn) //instead of emitting true/false, emit the value of this function
    .take(1) //this ensures the observable ends after we've gotten a response
    .toPromise(); //convert it all to a promise
}

requestWhenOnline(() => axios.get('http://example.com'))
  .then(console.log)
  .catch(console.error);