rxHelper.js

Array.prototype.concatAll = function() {
	var results = [];
	this.forEach(function(subArray) {
		results.push.apply(results, subArray);
	});

	return results;
};

Array.prototype.concatMap = function(fn) {
	return this.
		map(function(item) {
			return fn(item);
		}).concatAll();
};

Array.prototype.reduce = function(combiner, initialValue) {
	var counter,
		accumulatedValue;

	if (this.length === 0) {
		return this;
	}
	else {
		if (arguments.length === 1) {
			counter = 1;
			accumulatedValue = this[0];
		}
		else if (arguments.length >= 2) {
			counter = 0;
			accumulatedValue = initialValue;
		}
		else {
			throw "Invalid arguments.";
		}
		while(counter < this.length) {
			accumulatedValue = combiner(accumulatedValue, this[counter]);
			counter++;
		}
		return [accumulatedValue];
	}
};

Array.prototype.zip = function(left, right, combinerFunction) {
	var counter,
		results = [];

	for(counter = 0; counter < Math.min(left.length, right.length); counter++) {
		results.push(combinerFunction(left[counter],right[counter]));
	}

	return results;
};