1 var gCounter = 0;

     2 

     3 function FooBar() {

     4 	this.counter = ++gCounter;

     5 }

     6 

     7 FooBar.prototype.doFoo = function() {

     8 

     9 	return this.counter;

    10 }

    11 

    12 FooBar.prototype.doBar = function() {

    13 

    14 	return this.counter;

    15 }

    16 

    17 FooBar.prototype.propertyChanged = function(instance, propertyId) {

    18 	if (propertyId == "foo")

    19 		instance.properties.bar = instance.properties.foo;

    20 }