How to override the window.open functionality?

I know this reply is a little late, but I felt that a more general solution may be helpful for other people (trying to override other methods)

function wrap(object, method, wrapper){
    var fn = object[method];

    return object[method] = function(){
        return wrapper.apply(this, [fn.bind(this)].concat(
            Array.prototype.slice.call(arguments)));
    };
};

//You may want to 'unwrap' the method later 
//(setting the method back to the original)
function unwrap(object, method, orginalFn){
    object[method] = orginalFn;
};

//Any globally scoped function is considered a 'method' of the window object 
//(If you are in the browser)
wrap(window, "open", function(orginalFn){
    var originalParams = Array.prototype.slice.call(arguments, 1);
    console.log('open is being overridden');
    //Perform some logic
    //Call the original window.open with the original params
    orginalFn.apply(undefined, originalParams); 
});

To avoid circular calls, you need to stash away the original window.open function in a variable.

A nice way (that doesn't pollute the global namespace) is to use a closure. Pass the original window.open function to an anonymous function as an argument (called open below). This anonymous function is a factory for your hook function. Your hook function is permanently bound to the original window.open function via the open argument:

window.open = function (open) {
    return function (url, name, features) {
        // set name if missing here
        name = name || "default_window_name";
        return open.call(window, url, name, features);
    };
}(window.open);