Property Change Listeners in MontageJS

gistfile1.js

var bar = {a: {b: {c: 3}}};

// we're going to listen to changes of the bar.a.b.c value
bar.addPropertyChangeListener("a.b.c", function() {
    console.log("bar.a.b.c was changed to: " + bar.a.b.c);
});
bar.a.b.c = 4; // Outputs: bar.a.b.c was changed to: 4
bar.a = {b: {c: 6}}; // Outputs: bar.a.b.c was changed to: 6
bar.a.b.c = 3 + 3; // notification not fired, the value didn't change

// a third parameter indicates that the listener should be called before
// the change happens
bar.addPropertyChangeListener("a.b.c", function() {
    console.log("bar.a.b.c is going to be changed from: " + bar.a.b.c);
}, true);

bar.a.b.c = 4; // Outputs bar.a.b.c is going to be changed from: 6
               //         bar.a.b.c was changed to: 4