Receiving and relaying 3rd party site content with client script?

Question

JavaScript

Is it possible?

A client on our site mysite.com clicks on a link, for example mysite.com/product123.html
our server sends a page to the browser, something like this :header, body: our-javascript , footer.
In the body, our script, working from the client side, loads data from a third-party site othersite.com/product456, saving the work of third-party site scripts, replaces the header and footer of the received page with ours, as well as the text of links from othersite.com/ to mysite.com/ the next time the client clicks
on the changed link, the script will re-encode it and re-request the content of the third-party site, so
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The task is to:
2. when links were replaced, the functionality of a third-party site (scripts, ajax) was not lost during retransmission.

Answer 1

XD
Only possible if the third party site explicitly states that your site can make requests to their site.

Answer 2

with a reasonable security policy, a third-party site will quickly "cover" this kind of "load", and your site will fall down in the search results