Changing select/map to use a scoped this argument in addition to passing the observable sequence.

docs.md

Changing select/map to use a scoped this argument in addition to passing the observable sequence.

Changes from:

  selector: (T => Int => U)

to:

  selector: (T => Int => Observable<T> => U)

With optional scope binding.

This also affects

• every
• some
• filter

map.js

/**
 *  Projects each element of an observable sequence into a new form by incorporating the element's index.
 *  
 *  1 - source.select(function (value) { return value * value; });
 *  2 - source.select(function (value, index) { return value * value + index; });
 *      
 * @memberOf Observable#
 * @param {Function} selector A transform function to apply to each source element; the second parameter of the function represents the index of the source element.
 * @returns {Observable} An observable sequence whose elements are the result of invoking the transform function on each element of source. 
 */
observableProto.map = function (selector) {
    var parent = this, thisArg = arguments[1];
    return new AnonymousObservable(function (observer) {
        var count = 0;
        return parent.subscribe(function (value) {
            var result;
            try {
                result = selector.call(thisarg, value, count++, parent);
            } catch (exception) {
                observer.onError(exception);
                return;
            }
            observer.onNext(result);
        }, observer.onError.bind(observer), observer.onCompleted.bind(observer));
    });
};