What are the libraries (scripts) for autocomplete documents?

Question

JavaScript

Good afternoon
I see sites on the network from time to time,
for example
roszkh.ru
Fill in the tables on the site, they are processed on the server and automatically enter your data into documents
Documents are issued to you (sent to the destination)
Need such automation
Advice is accepted in any languages
​​Thank you

Answer 1

We open the page in our browser (based on any solution in any language, usually some kind of WebBrowser control) in a couple of dozen lines of code and inject our own javascript into it, which emulates user actions, usually this is a very simple code, it is more difficult when the forms are multi-stage.
The solution is universal, there is not a single protection against automation that this solution could not deceive (but it is possible to create difficulties, since it is difficult to emulate keyboard clicks correctly in some cases).
I wrote something similar in java, there were experiments on mono (c#) quite a long time ago, it uses a firefox-based engine, it works well in a headless version on any cheap vps.
If there is no need to hide the interface (running as a service), you can use any browser plugins (the same tempermonkey / greasemonkey) and implement everything completely in javascript.