function Foo(value) {
this.value = value;
}
Foo.prototype.valueOf = function () {
return this.value;
};
var first = new Foo(2) // first.val = 2
var two = new Foo(3) // first.val = 3
alert( first + two ) // должно вывести 5obj = decorate(obj, 'val', function (delegate) {
return function () {
return delegate.apply(this, arguments);
}
});
function decorate(obj, prop, factory) {
obj[prop] = factory(obj[prop]);
return obj;
}