sample.js

  var SampleObservable = (function(__super__) {
    inherits(SampleObservable, __super__);
    function SampleObservable(source, sampler) {
      this.source = source;
      this._sampler = sampler;
      __super__.call(this);
    }

    SampleObservable.prototype.subscribeCore = function (o) {
      var state = {
        o: o,
        atEnd: false,
        value: null,
        hasValue: false,
        sourceSubscription: new SingleAssignmentDisposable()
      };

      state.sourceSubscription.setDisposable(this.source.subscribe(new SampleSourceObserver(state)));
      return new BinaryDisposable(
        state.sourceSubscription,
        this._sampler.subscribe(new SamplerObserver(state))
      );
    };

    return SampleObservable;
  }(ObservableBase));

  var SamplerObserver = (function(__super__) {
    inherits(SamplerObserver, __super__);
    function SamplerObserver(s) {
      this._s = s;
      __super__.call(this);
    }

    SamplerObserver.prototype._handleMessage = function () {
      if (this._s.hasValue) {
        this._s.hasValue = false;
        this._s.o.onNext(this._s.value);
      }
      this._s.atEnd && this._s.o.onCompleted();
    };

    SamplerObserver.prototype.next = function () { this._handleMessage(); };
    SamplerObserver.prototype.error = function (e) { this._s.onError(e); };
    SamplerObserver.prototype.completed = function () { this._handleMessage(); };

    return SamplerObserver;
  }(AbstractObserver));

  var SampleSourceObserver = (function(__super__) {
    inherits(SampleSourceObserver, __super__);
    function SampleSourceObserver(s) {
      this._s = s;
      __super__.call(this);
    }

    SampleSourceObserver.prototype.next = function (x) {
      this._s.hasValue = true;
      this._s.value = x;
    };
    SampleSourceObserver.prototype.error = function (e) { this._s.o.onError(e); };
    SampleSourceObserver.prototype.completed = function () {
      this._s.atEnd = true;
      this._s.sourceSubscription.dispose();
    };

    return SampleSourceObserver;
  }(AbstractObserver));

  /**
   *  Samples the observable sequence at each interval.
   *
   * @example
   *  1 - res = source.sample(sampleObservable); // Sampler tick sequence
   *  2 - res = source.sample(5000); // 5 seconds
   *  2 - res = source.sample(5000, Rx.Scheduler.timeout); // 5 seconds
   *
   * @param {Mixed} intervalOrSampler Interval at which to sample (specified as an integer denoting milliseconds) or Sampler Observable.
   * @param {Scheduler} [scheduler]  Scheduler to run the sampling timer on. If not specified, the timeout scheduler is used.
   * @returns {Observable} Sampled observable sequence.
   */
  observableProto.sample = function (intervalOrSampler, scheduler) {
    isScheduler(scheduler) || (scheduler = defaultScheduler);
    return typeof intervalOrSampler === 'number' ?
      new SampleObservable(this, observableinterval(intervalOrSampler, scheduler)) :
      new SampleObservable(this, intervalOrSampler);
  };