`Rx.Observable.case(selector, sources, [elseSource|scheduler])`

Uses selector to determine which source in sources to use. There is an alias 'switchCase' for browsers <IE9.

Arguments

selector (Function): The function which extracts the value for to test in a case statement.
sources (Object): A object which has keys which correspond to the case statement labels.
[elseSource|scheduler] (Observable | Scheduler): The observable sequence that will be run if the sources are not matched. If this is not provided, it defaults to Rx.Observabe.empty with the specified scheduler.

Returns

(Observable): An observable sequence which is determined by a case statement.

Example

var sources = {
    'foo': Rx.Observable.return(42),
    'bar': Rx.Observable.return(56)
};

var defaultSource = Rx.Observable.empty();

var source = Rx.Observable.case(
    function () {
        return 'foo';
    },
    sources,
    defaultSource);

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

//=> Next: 42
//=> Completed