Whether this is trivial or impossible depends on the specifics of how the page gets the data.
If the JS on the page just uses an XHR to grab the data, it's trivial - ignore the page and go straight for the URL with the data. It might even return it in JSON format for you :-P
If they're doing something dumb, it could be a much bigger deal.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Whether this is trivial or impossible depends on the specifics of how the page gets the data.
If the JS on the page just uses an XHR to grab the data, it's trivial - ignore the page and go straight for the URL with the data. It might even return it in JSON format for you :-P
If they're doing something dumb, it could be a much bigger deal.