var subject = new Rx.BehaviorSubject(0); // 0 為起始值

var observerA = {

    next: value => console.log('A next: ' + value),

    error: error => console.log('A error: ' + error),

    complete: () => console.log('A complete!')

}

​

var observerB = {

    next: value => console.log('B next: ' + value),

    error: error => console.log('B error: ' + error),

    complete: () => console.log('B complete!')

}

​

subject.subscribe(observerA);

// "A next: 0"

subject.next(1);

// "A next: 1"

subject.next(2);

// "A next: 2"

subject.next(3);

// "A next: 3"

​

setTimeout(() => {

    subject.subscribe(observerB); // 3 秒後才訂閱，observerB 不會收到任何值。

     "B next: 3"

},3000)