Glitch

bacon.js

var Bacon = require("baconjs");

var aBus = new Bacon.Bus();
a = aBus.toProperty(3);

b = a.map(function (x) { return x * 2; });
c = a.map(function (x) { return x * 3; });

d = Bacon.combineWith(function (x, y) { return x + y; }, b, c);

d.onValue(function (x) {
	console.log("next", x);
});

aBus.push(4);

output.txt

% node rx.js 
next 15
next 17
next 20

% node bacon.js 
next 15
next 20

rx.js

var Rx = require("rx");

var a = new Rx.BehaviorSubject(3);

b = a.map(function (x) { return x * 2; });
c = a.map(function (x) { return x * 3; });

d = b.combineLatest(c, function (x, y) { return x + y; });

d.subscribe(function (x) {
	console.log("next", x);
}, function (x) {
	console.log("err", x);
}, function () {
	console.log("completed");
});

a.onNext(4);