Any way to read elements from another website in an iframe?

Question

I'm playing around with some stuff and trying to discern if when using a cross-domain iframe(post_message) if I can read the elements: div-tag p-tag etc of site within the iframe? I haven't seen any other posts on this, so hopefully someone can provide some insight.

Answer 1

postMessage allows you to communicate with a cooperating iframe. To use it, one window must send a message with postMessage and the other window must have an event listener listening for the message and it must process that message and do whatever you want done with it.

So, it is possible to use postMessage to retrieve content from an iframe, even a cross-origin iframe, but it requires that there be code in the iframe that can receive the message, understand what is being asked of it and do postMessage back to the original frame with the information that was requested.

So, this means that if you control both the window and iframe javascript, you can do what you ask, but if you don't control one of the two and they don't already have the right javascript code in them to fetch the data you want, then you can't get the job done with postMessage. All it does is deliver messages. The code to process those messages must be put there by the owner of that particular web page.