JavaScript does not have any print object or print methods.
You cannot access output devices from JavaScript.
The only exception is that you can call the window.print() method in the browser to print the content of the current window.
so you can put a button on the page, that calls window.print() (in javascript) then (also in javascript) triggers the print button.
It's not really a shock to discover that "silent printing from your browser" is a no-no, because well, spam.
Cheers
Bruce