takelast.js

  var TakeLastObserver = (function (__super__) {
    inherits(TakeLastObserver, __super__);
    function TakeLastObserver(o, c) {
      this._o = o;
      this._c = c;
      this._q = [];
      __super__.call(this);
    }

    TakeLastObserver.prototype.next = function (x) {
      this._q.push(x);
      this._q.length > this._c && this._q.shift();
    };

    TakeLastObserver.prototype.error = function (e) {
      this._o.onError(e);
    };

    TakeLastObserver.prototype.completed = function () {
      while (this._q.length > 0) { this._o.onNext(this._q.shift()); }
      this._o.onCompleted();
    };

    return TakeLastObserver;
  }(AbstractObserver));

  /**
   *  Returns a specified number of contiguous elements from the end of an observable sequence.
   * @description
   *  This operator accumulates a buffer with a length enough to store elements count elements. Upon completion of
   *  the source sequence, this buffer is drained on the result sequence. This causes the elements to be delayed.
   * @param {Number} count Number of elements to take from the end of the source sequence.
   * @returns {Observable} An observable sequence containing the specified number of elements from the end of the source sequence.
   */
  observableProto.takeLast = function (count) {
    if (count < 0) { throw new ArgumentOutOfRangeError(); }
    var source = this;
    return new AnonymousObservable(function (o) {
      return source.subscribe(new TakeLastObserver(o, count));
    }, source);
  };