Javascript shopping code? [on hold]

I have a client that doesn't want to add a shopping Cart but a simple contact-like form. In other words, let's say there's this T-shirt and someone clicks on buy. He wants the button to redirect him to a contact form with the "unique" code of the T-shirt automatically written inside the subject. Is it possible to do that by a click function or anything? I am new to JavaScript, I would appreciate all help.