Cross domain request, javascript. How to get one number from a page?

Question

JavaScript

There is a page with information on it. How to get one number from this data? Preferably pure JS, without connecting these newfangled libraries of yours.
The main problem is that I don't understand how to connect to the page. If you run the script on it, then everything is elementary, document.getElementsBy ... But from another page I don’t understand how to do the same. I was expecting something like connect("example.com"); document.getElementsBy ...
No matter how. I've been digging around, but never got close to finding a solution.
Maybe there is an example of code in pure JS with getting any data from any page?

Answer 1

without a server-side language, you won't crank if you want to steal data without the permission of that page.
what we need: we make a request to our server, and it is already looking at that page and parsing it, and we use the answer further.
I can help you implement.

Answer 2

If the site does not allow cross-domain requests for JS or Flash, then no way, proxy with your server, or maybe it makes sense to look for an API.

Answer 3

XMLHttpRequest

Answer 4

Let your friend allow cross-requests from your site or give pure js code, possibly also with referrer check. Or what he pumps out should be uploaded to your server.
Until I realized what the snag is and what the possibilities are.