[EMAIL MODULE] I can't seem to get my JS variables to display in the body of the email which is a st

I'm writing a script in SandBox that sends a email to a customer when they purchase from specific vendors. I'm using the email module and a string consisting of HTML for the body of the email. The email sends just fine and the HTML table itself is formatted correctly and displaying just fine, but I need to be able to use some javascript variables like customer name, items in order, department purchased from, etc in the HTML body of the email, but using something like document.getElementById().innerHTML doesn't seem to be working. I was wondering if there is a work around