combinelatest.js

  function falseFactory() { return false; }
  function argumentsToArray() {
    var len = arguments.length, args = new Array(len);
    for(var i = 0; i < len; i++) { args[i] = arguments[i]; }
    return args;
  }

  var CombineLatestObservable = (function(__super__) {
    inherits(CombineLatestObservable, __super__);
    function CombineLatestObservable(params, cb) {
      this._params = params;
      this._cb = cb;
      __super__.call(this);
    }

    CombineLatestObservable.prototype.subscribeCore = function(observer) {
      var len = this._params.length,
          subscriptions = new Array(len);

      var state = {
        hasValue: arrayInitialize(len, falseFactory),
        hasValueAll: false,
        isDone: arrayInitialize(len, falseFactory),
        values: new Array(len)
      };

      for (var i = 0; i < len; i++) {
        var source = this._params[i], sad = new SingleAssignmentDisposable();
        subscriptions[i] = sad;
        isPromise(source) && (source = observableFromPromise(source));
        sad.setDisposable(source.subscribe(new CombineLatestObserver(observer, i, this._cb, state)));
      }

      return new NAryDisposable(subscriptions);
    };

    return CombineLatestObservable;
  }(ObservableBase));

  var CombineLatestObserver = (function (__super__) {
    inherits(CombineLatestObserver, __super__);
    function CombineLatestObserver(o, i, cb, state) {
      this._o = o;
      this._i = i;
      this._cb = cb;
      this._state = state;
      __super__.call(this);
    }

    function notTheSame(i) {
      return function (x, j) {
        return j !== i;
      };
    }

    CombineLatestObserver.prototype.next = function (x) {
      this._state.values[this._i] = x;
      this._state.hasValue[this._i] = true;
      if (this._state.hasValueAll || (this._state.hasValueAll = this._state.hasValue.every(identity))) {
        var res = tryCatch(this._cb).apply(null, this._state.values);
        if (res === errorObj) { return this._o.onError(res.e); }
        this._o.onNext(res);
      } else if (this._state.isDone.filter(notTheSame(this._i)).every(identity)) {
        this._o.onCompleted();
      }
    };

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

    CombineLatestObserver.prototype.completed = function () {
      this._state.isDone[this._i] = true;
      this._state.isDone.every(identity) && this._o.onCompleted();
    };

    return CombineLatestObserver;
  }(AbstractObserver));

  /**
  * Merges the specified observable sequences into one observable sequence by using the selector function whenever any of the observable sequences or Promises produces an element.
  *
  * @example
  * 1 - obs = Rx.Observable.combineLatest(obs1, obs2, obs3, function (o1, o2, o3) { return o1 + o2 + o3; });
  * 2 - obs = Rx.Observable.combineLatest([obs1, obs2, obs3], function (o1, o2, o3) { return o1 + o2 + o3; });
  * @returns {Observable} An observable sequence containing the result of combining elements of the sources using the specified result selector function.
  */
  var combineLatest = Observable.combineLatest = function () {
    var len = arguments.length, args = new Array(len);
    for(var i = 0; i < len; i++) { args[i] = arguments[i]; }
    var resultSelector = isFunction(args[len - 1]) ? args.pop() : argumentsToArray;
    Array.isArray(args[0]) && (args = args[0]);
    return new CombineLatestObservable(args, resultSelector);
  };