JavaScript Object Decorator

Question

I have a JavaScript object that has multiple methods:

var actualObject = {

    foo: function(){},
    bar: function(){},
    …

}

However, the actual object that I want people to use is proxy . It should forward all its calls to actualObject . The simplest way of doing that would be simply assigning actualObject to proxy .

proxy = actualObject;

However, for some methods, I want proxy to have additional functionality.

proxy.bar = function(arguments) {
    console.log('do something beforehand');
    actualObject.bar(arguments);
    console.log('do something afterward');
}

The problem is, if proxy and actualObject are the same, this overridden bar method will cause a recursion. Thus my question: What is the most "idiomatic" way of cloning a JavaScript object but overriding certain methods in a way that would allow calling the original methods from within the overriding ones?

Answer 1

Have the proxy prototype to be actualObject then define the function in proxy :

var proxy = Object.create(actualObject);

proxy.bar = function(arguments) {
    console.log('do something beforehand');
    actualObject.bar(arguments);
    console.log('do something afterward');
}