"Silent" printing for multiple printers - printing

Question

Well, I have a web-based application (written in Elixir/Phoenix framework). It's kind of POS for the restaurant.
The system runs on the rpi 3 with two accessible printers. One is local via USB, one is a network printer, connected through the WIFI router. Both of the printers were set up with CUPS and work fine, when I need to print something.
I'm using the Chromium browser, and the "--kiosk --kiosk-printing" switches. However this is where it gets tricky.
As I'm using the kiosk-printing, the printing dialog box (to select printer) doesn't come up, and defaults to the default printer, when sending a job. I need to use silent printing, because of automation. So the waiters don't need to select printer every single time.
Within the web-app, I have certain div's that needs to be printed to one printer, and other's to another. I'm using simple JS to print, however I cannot specify purely with JS/HTML which printer to use, for which job. (One printer to print bills, second printer to print orders to the kitchen)
What I need is to send jobs to different printers. Not sure how to make it, but any advise appreciated.
Thanks in advance!
Update: Found Jsprintsetup add-on for Firefox that might help. Will test now.
Update 2: Following the suggestion from #tkowal I was able to do what I need. I ended up creating individual tmp files (instead of sending div) and sending them for printing. Here is my code, if you're interested (tested on OSX):
# Generating tmp for printing and sending jobs
for item <- order_items do
file_name = Enum.join([item.order_id, "-", item.id, ".txt"], "")
file_create = Enum.join(["touch", file_name], " ")
file_create |> String.to_char_list |> :os.cmd
file_inject = Enum.join(["echo", item.food.name, item.quantity, ">", file_name], " ")
file_inject |> String.to_char_list |> :os.cmd
# Send to print
print_path = Enum.join(["~/Developer/elixir/myApp/", file_name], "")
file_print = Enum.join(["lp", "-d", "HP_LaserJet_3050", print_path], " ")
file_print |> String.to_char_list |> :os.cmd
# Remove tmp file
file_remove = Enum.join(["rm", file_name], " ")
file_remove |> String.to_char_list |> :os.cmd
end

Answer 1

You can use System.cmd/3 to interact with operating system. It would be good to come up with a command line solution to printing whatever you need and then calling it through controller in your Phoenix application.
Browsers are sandboxes and can't access everything in your operating system, but your server side code should be able to do almost anything.