Unsubscribe from RxJS Observables

Question

I have these two objects, and I want to stop listening to their events. I am totally new to observables and RxJS and just trying to work with the Inquirer library.

Here is the RxJS API for reference: http://reactivex.io/rxjs/class/es6/Observable.js~Observable.html

How can I unsubscribe from these types of observables?

ConnectableObservable:

   ConnectableObservable {
     source: EventPatternObservable { _add: [Function], _del: [Function], _fn: undefined },
     _connection: ConnectDisposable { _p: [Circular], _s: [Object] },
     _source: AnonymousObservable { source: [Object], __subscribe: [Function: subscribe] },
     _subject: 
      Subject {
        isDisposed: false,
        isStopped: false,
        observers: [Object],
        hasError: false } },
  _count: 1,
  _connectableSubscription: 
   ConnectDisposable {
     _p: 
      ConnectableObservable {
        source: [Object],
        _connection: [Circular],
        _source: [Object],
        _subject: [Object] },
     _s: AutoDetachObserver { isStopped: false, observer: [Object], m: [Object] } } }

FilterObservable:

FilterObservable {
  source: 
   RefCountObservable {
     source: 
      ConnectableObservable {
        source: [Object],
        _connection: [Object],
        _source: [Object],
        _subject: [Object] },
     _count: 1,
     _connectableSubscription: ConnectDisposable { _p: [Object], _s: [Object] } },
  predicate: [Function] }

I need to unsubscribe from these objects:

'use strict';
var rx = require('rx');

function normalizeKeypressEvents(value, key) {
  return {value: value, key: key || {}};
}

module.exports = function (rl) {

  var keypress = rx.Observable.fromEvent(rl.input, 'keypress', normalizeKeypressEvents)
    .filter(function (e) {
      // Ignore `enter` key. On the readline, we only care about the `line` event.
      return e.key.name !== 'enter' && e.key.name !== 'return';
    });

  return {
    line: rx.Observable.fromEvent(rl, 'line'),

    keypress: keypress,

    normalizedLeftKey: keypress.filter(function (e) {
      return e.key.name === 'left';
    }).share(),

    normalizedRightKey: keypress.filter(function (e) {
      return e.key.name === 'right';
    }).share(),

    normalizedUpKey: keypress.filter(function (e) {
      return e.key.name === 'up' || e.key.name === 'k' || (e.key.name === 'p' && e.key.ctrl);
    }).share(),

    normalizedDownKey: keypress.filter(function (e) {
      return e.key.name === 'down' || e.key.name === 'j' || (e.key.name === 'n' && e.key.ctrl);
    }).share(),

    numberKey: keypress.filter(function (e) {
      return e.value && '123456789'.indexOf(e.value) >= 0;
    }).map(function (e) {
      return Number(e.value);
    }).share(),

    spaceKey: keypress.filter(function (e) {
      return e.key && e.key.name === 'space';
    }).share(),

    aKey: keypress.filter(function (e) {
      return e.key && e.key.name === 'a';
    }).share(),

    iKey: keypress.filter(function (e) {
      return e.key && e.key.name === 'i';
    }).share()
  };
};

My current best guess is that no explicit call to subscribe is happening like this:

var source = Rx.Observable.fromEvent(input, 'click');

var subscription = source.subscribe(
  function (x) {
    console.log('Next: Clicked!');
  },
  function (err) {
    console.log('Error: %s', err);
  },
  function () {
    console.log('Completed');
  });

but instead, there are these calls:

events.normalizedUpKey.takeUntil(validation.success).forEach(this.onUpKey.bind(this));
events.normalizedDownKey.takeUntil(validation.success).forEach(this.onDownKey.bind(this));

so my best guess is that I need a way to nullify/cancel the takeUntil call.

Answer 1

If you want to unsubscribe you need to have the Subscription object. That's the object returned from every Observable.subscribe() call. For example:

let subscriber = Observable.subscribe(...);
...
subscriber.unsubscribe();

For more info see: https://github.com/ReactiveX/rxjs/blob/master/doc/subscription.md

Answer 2

I second what the first commenter was saying. However it feels that there needs to be a call like this somewhere in the code:

let subscription = normalizedUpKey.subscribe( data => console.log('data') );

that you could do

subscription.unsubscribe()

on. How else would you know when something happens, or is that part of the 3rd party library?

To read more about Rxjs. I suggest you have a look at this free book, https://www.gitbook.com/book/chrisnoring/rxjs-5-ultimate/details