I think the majority of exploits in metasploit are for Linux, but could be wrong.

Malware for Linux is a thing. I see it every day.

What if the virus is written in javascript

You accidentally click it and wine starts launching:

Way back in 2003, I had a school project partner over to do some work on a project. They had a floppy that was infected with some malicious stuff and had planned to utterly trash my computer with it. I only found out at a later date because some guys were asking me questions about my computer, and someone spilled the beans whenever they realised that my computer wasn't infected and was indeed still functioning completely fine....