Accessing “pre” tag in an iframe loading a page from different domain

Question

I am trying to load aa page into an iframe. When that page is loaded i wish to edit the contents of the "pre" tag which is inside the loaded document. The loaded doc is from another domain. I am using : resultframe is the iframe

var atag= document.getElementById("resultframe").contentWindow.document.getElementsByTagName('pre');
 atag[0].innerHTML="done";

to access the tag.

problem: there seems to be no effect of this statement. I need to know the correct syntax and also that can i access the elements of pages loaded from different domain. I got the syntax from the web and also some variation of it. Please suggest.

Answer 1

While JavaScript is limited by cross-domain policies that prevent interaction with another domain, there is one potential workaround as long as you can live with certain limitations.

By using something like PHP and it's cURL library you can grab the contents of a page from just about anywhere (even a secure page or one that requires a login, as long as you have credentials). You can then parse the page, edit what you need to, and display it within your own site. It's important to realize, though, that this is simply your own local copy of the page. You won't have the luxury of actually changing the contents of the page itself.

Another possibility, which would require access to all domains you wish to edit, would be to employ a web service that would accept edits in the form of a PUT request. You can achieve a lot more with a web service, but it would have to be available on all target domains that you wish to make changes to.

In the near future, XMLHttpRequest Level 2 might become a reality and will bring Cross-Origin Resource Sharing (CORS) with it. CORS will allow web applications on one domain to make cross domain AJAX requests to another domain. The target domain will have a header giving express permission to allow requests from another. Potentially, this could be used to send edits to another site.

Answer 2

You can't. Browsers have cross-domain policies, for security reasons.

What if I included the facebook page in an iframe, and I can get all your information because you're always connected to it?