I need some help with the .js file to open a cash drawer in the point of sale module. I have managed to add a custom button (https://ibb.co/bgbNbrB) on the payment-screen but up to this point I haven't done js and am not sure where to start.

We have a rs232 cash box which is currently attached to the thermal printer and only opens when a receipt is printed. I would like to connect the cash box directly to the computer and open manually using my custom button when required, or even extend the code and add to the "validate" button instead.