javascript - Storing observer in a global variable and use it later

Question

How can I create an observable and generate the next value later in the code? I would like to be able to call onNext from different parts of the code as a result of other async events.

This is what I have tried, which doesn't work:

var Rx = require('rx');

var GlobalObserver;

var source = Rx.Observable.create(observer => {
    GlobalObserver = observer;
});

var subscription = source.subscribe(
    x => console.log('onNext: %s', x),
    e => console.log('onError: %s', e),
    () => console.log('onCompleted')
);

//...later in the code, as a result of another async event:


    GlobalObserver.onNext(someData);
    ...
    GlobalObserver.onNext(someOtherData);

Answer 1

What you need is a subject of some sort. ReplaySubject, BehaviorSubject, Subject, etc.

Create a subject, then you can do subject.subscribe(...) to subscribe to it. You can also do subject.onNext(...) to add to the stream.

For example:

var subject = new Rx.Subject();

var subscription = subject.subscribe(
    function (x) { console.log('onNext: ' + x); },
    function (e) { console.log('onError: ' + e.message); },
    function () { console.log('onCompleted'); }
);

subject.onNext(1);
// => onNext: 1

subject.onNext(2);
// => onNext: 2

subject.onCompleted();
// => onCompleted

subscription.dispose();

A more specific use case (will add to the observable stream every time a successful HTTP response comes back):

var httpResponseStream = new Rx.Subject();

var subscription = httpResponseStream.subscribe(function (response) { 
    console.log('HTTP response success: ', response); 
});

makeAJAXCall().then(function (response) {
    httpResponseStream.onNext(response);
});

As another user stated, make sure you change all onNext's to next if you are using V5. If you are using V4, stick to onNext.