const myPromise = val => new Promise(resolve => setTimeout(() => resolve(`Result: ${val}`), 2000))

//emit 1,2,3

const source = Rx.Observable.of(1,2,3);

​

const example = source

  //map each value to promise

  .map(val => myPromise(val))

  //emit result from source

  .mergeAll();

​

/*

  output:

  "Result: 1"

  "Result: 2"

  "Result: 3"

*/

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