This is RxJS v 4. Find the latest version here

`Rx.Observable.prototype.mergeAll()`

`Rx.Observable.prototype.mergeObservable()` DEPRECATED

Merges an observable sequence of observable sequences into an observable sequence.

Returns

(Observable): The observable sequence that merges the elements of the inner sequences.

Example

var source = Rx.Observable.range(0, 3)
  .map(function (x) { return Rx.Observable.range(x, 3); })
  .mergeAll();

var subscription = source.subscribe(
  function (x) {
    console.log('Next: %s', x);
  },
  function (err) {
    console.log('Error: %s', err);
  },
  function () {
    console.log('Completed');
  });

// => Next: 0
// => Next: 1
// => Next: 1
// => Next: 2
// => Next: 2
// => Next: 2
// => Next: 3
// => Next: 3
// => Next: 4
// => Completed