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var sources = {

    'foo': Rx.Observable.return(42),

    'bar': Rx.Observable.return(56)

};

​

var defaultSource = Rx.Observable.empty();

​

var source = Rx.Observable.case(

    () => 'foo',

    sources,

    defaultSource);

​

var subscription = source.subscribe(

  x => console.log(`onNext: ${x}`),

  e => console.log(`onError: ${e}`),

  () => console.log('onCompleted'));

​

//=> onNext: 42 

//=> onCompleted