Question

I am loading a website’s content in an iframe through a proxy on my server. If I add this javascript at the top of the file,

var top = "";
var parent = "";

I can successfully prevent the website from frame busting. How can I do this and still access functions in the parent window, like this:

parent.my_function('this is called from inside the iframe');

Answer 1

I’m not at all sure overwriting those variables necessarily prevents frame busting, but if it’s working for you, presumably to access parent you can do something like this:

(function() {
    var oldParent = window.parent;

    window.parent = "";
    // ...
})();

…and access oldParent within the function.

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Separately, note that

var window.top = "";

and

var window.parent = "";

…are both syntax errors. You use var to declare variables, not properties of named objects.

If you’re at global scope, var top would create a property on window if there weren’t already one, but if there’s one already (and there is), it’s a no-op and the var portion is ignored entirely (the assignment portion is still processed). Absent syntax errors, your four lines boil down to:

top = "";
parent = "";

or

window.top = "";
window.parent = "";

…which are equivalent if top and parent exist on window (and they do).