Printing without print screen

Question

I am trying to create a custom web app that will be run from specific locations. I would like to print without any preview and preset screens (basically all the settings need to be saved beforehand on the browser / in the code) so that the user clicks on "Print" and no windows are opened, but the paper gets printed. How could I do that? I was thinking of using an iPad as the hardware but am open to other solutions. Thanks a lot in advance!!!!