Overriding a JavaScript function while referencing the original

Question

I have a function, a(), that I want to override, but also have the original a() be performed in an order depending on the context. For example, sometimes when I'm generating a page I'll want to override like this:

function a() {
    new_code();
    original_a();
}

and sometimes like this:

function a() {
    original_a();
    other_new_code();
}

How do I get that original_a() from within the over-riding a()? Is it even possible?

Please don't suggest alternatives to over-riding in this way, I know of many. I'm asking about this way specifically.

Answer 1

You could do something like this:

var a = (function() {
    var original_a = a;

    if (condition) {
        return function() {
            new_code();
            original_a();
        }
    } else {
        return function() {
            original_a();
            other_new_code();
        }
    }
})();

Declaring original_a inside an anonymous function keeps it from cluttering the global namespace, but it's available in the inner functions.

Like Nerdmaster mentioned in the comments, be sure to include the () at the end. You want to call the outer function and store the result (one of the two inner functions) in a, not store the outer function itself in a.