Help w/RPi3 in Kiosk mode

I have a Raspberry Pi 3 and have it set up in Kiosk mode using the Chromium browser, thus when the Pi boots up, it opens up the browser and opens up a web site in full screen. The part I need help…I need to execute a script of some sort to log into the web site.

I have a script which was written in javascript which should work, but I don’t know how to get it executed.

If someone is familiar with Chromium and Pi, if you could give me some advice I would greatly appreciate it.

Thanks, Rick