Rx.Observer.prototype.toNotifier()
Creates a notification callback from an observer.
返回值
(Function): The function that forwards its input notification to the underlying observer.
Example
var observer = Rx.Observer.create(
x => console.log(`onNext: ${x}`),
e => console.log(`onError: ${e}`),
() => console.log('onCompleted'));
var notifier = observer.toNotifier();
// Invoke with onNext
notifier(Rx.Notification.createOnNext(42));
// => onNext: 42
// Invoke with onCompleted
notifier(Rx.Notification.createOnCompleted());
// => onCompleted