const myPromise = val => new Promise(resolve => setTimeout(() => resolve(`Promise Resolved: ${val}`), 5000))

​

/*

  when all observables complete, give the last

  emitted value from each as an array

*/

const example = Rx.Observable.forkJoin(

  //emit 'Hello' immediately

  Rx.Observable.of('Hello'),

  //emit 'World' after 1 second

  Rx.Observable.of('World').delay(1000),

  //emit 0 after 1 second

  Rx.Observable.interval(1000),

  //emit 0...1 in 1 second interval

  Rx.Observable.interval(1000).take(2),

  //promise that resolves to 'Promise Resolved' after 5 seconds

  myPromise('RESULT')

);

//output: ["Hello", "World", 0, 1, "Promise Resolved: RESULT"]

const subscribe = example.subscribe(val => console.log(val));

​

//make 5 request

const queue = Rx.Observable.of([1,2,3,4,5]);

//emit array of all 5 results

const exampleTwo = queue

  .mergeMap(q => Rx.Observable.forkJoin(...q.map(myPromise)));

/*

  output:

  [

   "Promise Resolved: 1", 

   "Promise Resolved: 2", 

   "Promise Resolved: 3", 

   "Promise Resolved: 4",    

   "Promise Resolved: 5"

  ]

*/

const subscribeTwo = exampleTwo.subscribe(val => console.log(val));