When you want to get the current value of a subject, you need to switch BehaviorSubject, it always emit the latest value or throw error.

Then you can call 'getValue()':

var subject = new Rx.BehaviorSubject(56);console.log('Value is: ' + subject.getValue());// => Value is: 56subject.onNext(42);console.log('Value is: ' + subject.getValue());// => Value is: 42subject.onCompleted();subject.onNext(100);console.log('Value is frozen: ' + subject.getValue());// => Value is frozen: 42subject.dispose();try {    subject.getValue();} catch (e) {    console.log(e.message);}// => Object has been disposed