iframe如何访问其父DOM？

Question

How is it possible for a script within an <iframe> to have any notion of the page containing it? Can a script in the frame access any context outside of it? What about cross-domain?

Up until now I believed an <iframe> is completely agnostic to the containing page, but I have seen an example which contradicts this belief.

What exactly can and can't be done from within an <iframe> with respect to the containing page?

Answer 1

If the content of the iframe and its parent have the same domain, you can access the parent pages DOM from the iframe by using parent.document.getElement... .

However you can't do this cross-domain (not even across different subdomains) as it will result in:

Uncaught DOMException: Blocked a frame with origin "https://example.com" from accessing a cross-origin frame.

Answer 2

Generally, you can't communicate between the two DOMs across domains. However, there is a way to pass messages between the two using the hash portion of the iframe's url. For iframes on the same domain, see oezi's answer .

This might be of some help , and there's plenty of other questions on the topic around here.

Answer 3

If they aren't on the same domain, you can communicate some information through the url fragment/hash. Here is a good example of that process...

http://www.tagneto.org/blogcode/xframe/ui.html