How to identify if a webpage is being loaded inside an iframe or directly into the browser window?

Question

I am writing an iframe based facebook app. Now I want to use the same html page to render the normal website as well as the canvas page within facebook. I want to know if I

Answer 1

It's an ancient piece of code that I've used a few times:

if (parent.location.href == self.location.href) {
    window.location.href = 'https://www.facebook.com/pagename?v=app_1357902468';
}