Ask/Take variables values from a server with Javascript script

Hello everyone, 

I'm working on a project where I would like my lesson to be able to ask my LRS or other server to send me info on the participant. 
I've seen a solution with an XML file, to read data in it with a Javascript code in my eLesson, but my goal would be to directly interact with one server (similar to the LRS). And I would like to know is someone already tried it.