Rx.Observable.prototype.flatMapObserver(onNext, onError, onCompleted, [thisArg]), Rx.Observable.prototype.selectManyObserver(onNext, onError, onCompleted, [thisArg])

Projects each notification of an observable sequence to an observable sequence and merges the resulting observable sequences into one observable sequence.

Arguments

1. onNext (Function): A transform function to apply to each element. The selector is called with the following information:
   1. the value of the element
   2. the index of the element
2. onError (Function): A transform function to apply when an error occurs in the source sequence.
3. onCompleted (Function): A transform function to apply when the end of the source sequence is reached.
4. [thisArg] (Any): Object to use as this when executing the transform functions.

Returns

(Observable): An observable sequence whose elements are the result of invoking the one-to-many transform function corresponding to each notification in the input sequence.

Example

var source = Rx.Observable.range(1, 3)
    .flatMapObserver(
        function (x, i) {
            return Rx.Observable.repeat(x, i);
        },
        function (err) {
            return Rx.Observable.return(42);
        },
        function () {
            return Rx.Observable.empty();
        });

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

// => Next: 2
// => Next: 3
// => Next: 3
// => Completed