Getting Iframes on mozilla

I'm using JavaScript on Mozilla开发者_开发问答 (version 4). Once I get a DOM object and identify the tag as an IFRAME I'd like to get the content and the borders (x,y pixels)of the IFRAME, (if I understand correctly the Iframe is an additional HTML page inside another HTML).

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Look here: https://developer.mozilla.org/en/DOM/HTMLIFrameElement

contentDocument and frameborder are probably what you are looking for.