HTML iFrame内容

Question

When I access the iframe with a=window.frames["iframe"] it says that a is a DOMWindow.
But when I try to access document it says undefined, but when I use top it refers back to it self. It's like the iframe only have itself as a property.
When i access it trough document.getElementById("iframe") it identifies itself as HTMLIFrame, but the problem still exists, this is really weird and i need help.

I have tried:

document.getElementById("iframe").getDocument
document.getElementById("iframe").getDocument()
document.getElementById("iframe").html.body
document.getElementById("iframe").body
document.getElementById("iframe").document.getElementById("btag")

and many more combinations.

I seriously do not know why it acts this way.

Thanks.

Answer 1

You need to access either the contentWindow or contentDocument depending on the browser.

I've done some light testing and it seems .document isn't working (I'm in chrome) this may be a better solution:

http://jsfiddle.net/sTkVR/4/

document.frames['frmID'] returns the equivalent as contentWindow or contentDocument which is why it says DOMWindow

Answer 2

The window.frames property is actually a circular reference to the window itself.

window.frames === window
window.frames === window.self

DOMWindow is an Array-like structure in that it has a length property and properties of numerical keys.

The window.frames property exists for the sole reason of providing access to frames by their numerical indexes such as window.frames[0] or just frames[0] . You could, of course, access the given frame as window[0] but that just does not look correct.

Elements of this pseudo-Array (accessed as frames[index] ) are instances of DOMWindow (in case of iframes, they point to iframe.contentWindow ) and you can access their document properties if they have a common origin with the current window (ie same protocols, domains and ports).

If you name a frame or an iframe (with an id attribute), they are (at least in WebKit-based browsers) mapped to properties of their owner window. In case of an iframe , the property points to the <iframe> element rather than to its contentWindow property.

// <iframe name="a">
frames['a'] === window['a'] === document.getElementById('a')