I'm facing a new problem.
I'm writing a scraper for a website, usually for this kind of tasks I use selenium, but in this case I cannot use anything that simulate a web-browser.
Researching on StackOverflow, I read the best solution is to undestand what javascript did and rebuild the request over HTTP.
Yeah, I understand well in theory, but don't know how to start, as I don't know well technologies involved. 
In my specific case, some HTML is added to the page when the button is clicked. With developer tools I set a breakpoint on the 'click' event, but from here, I'm literally lost. 
Anyone can link some resource and examples I can study?
In most cases, it is enougth to analyze the "network" tab of the developer tools and see the requests that are fired when you hit that button you metioned.  
As you understand those requests, you will be able to implement your scraper to run similar requests and grab the relevant data.
Python - Rebuild Javascript generated code using Requests Module