fromevent.js

  function isNodeList(el) {
    if (root.StaticNodeList) {
      // IE8 Specific
      // instanceof is slower than Object#toString, but Object#toString will not work as intended in IE8
      return el instanceof root.StaticNodeList || el instanceof root.NodeList;
    } else {
      return Object.prototype.toString.call(el) === '[object NodeList]';
    }
  }

  function ListenDisposable(e, n, fn) {
    this._e = e;
    this._n = n;
    this._fn = fn;
    this._e.addEventListener(this._n, this._fn, false);
    this.isDisposed = false;
  }
  ListenDisposable.prototype.dispose = function () {
    if (!this.isDisposed) {
      this._e.removeEventListener(this._n, this._fn, false);
      this.isDisposed = true;
    }
  };

  function createEventListener (el, eventName, handler) {
    var disposables = new CompositeDisposable();

    // Asume NodeList or HTMLCollection
    var elemToString = Object.prototype.toString.call(el);
    if (isNodeList(el) || elemToString === '[object HTMLCollection]') {
      for (var i = 0, len = el.length; i < len; i++) {
        disposables.add(createEventListener(el.item(i), eventName, handler));
      }
    } else if (el) {
      disposables.add(new ListenDisposable(el, eventName, handler));
    }

    return disposables;
  }

  /**
   * Configuration option to determine whether to use native events only
   */
  Rx.config.useNativeEvents = false;

  var EventObservable = (function(__super__) {
    inherits(EventObservable, __super__);
    function EventObservable(el, name, fn) {
      this._el = el;
      this._n = name;
      this._fn = fn;
      __super__.call(this);
    }

    function createHandler(o, fn) {
      return function handler () {
        var results = arguments[0];
        if (isFunction(fn)) {
          results = tryCatch(fn).apply(null, arguments);
          if (results === errorObj) { return o.onError(results.e); }
        }
        o.onNext(results);
      };
    }

    EventObservable.prototype.subscribeCore = function (o) {
      return createEventListener(
        this._el,
        this._n,
        createHandler(o, this._fn));
    };

    return EventObservable;
  }(ObservableBase));

  /**
   * Creates an observable sequence by adding an event listener to the matching DOMElement or each item in the NodeList.
   * @param {Object} element The DOMElement or NodeList to attach a listener.
   * @param {String} eventName The event name to attach the observable sequence.
   * @param {Object} eventListenerOptions An object describing EventListenerOptions
   * @param {Function} [selector] A selector which takes the arguments from the event handler to produce a single item to yield on next.
   * @returns {Observable} An observable sequence of events from the specified element and the specified event.
   */
  Observable.fromEvent = function (element, eventName, selector, eventListenerOptions) {
    // Node.js specific
    if (element.addListener) {
      return fromEventPattern(
        function (h) { element.addListener(eventName, h, eventListenerOptions); },
        function (h) { element.removeListener(eventName, h, eventListenerOptions); },
        selector);
    }

    // Use only if non-native events are allowed
    if (!Rx.config.useNativeEvents) {
      // Handles jq, Angular.js, Zepto, Marionette, Ember.js
      if (typeof element.on === 'function' && typeof element.off === 'function') {
        return fromEventPattern(
          function (h) { element.on(eventName, h, eventListenerOptions); },
          function (h) { element.off(eventName, h, eventListenerOptions); },
          selector);
      }
    }

    return new EventObservable(element, eventName, selector).publish().refCount();
  };