Answers for "how to make single javascript file for different html pages"

kill all server 5000 mac

#First run this, to get port information (with the port you want to kill)
sudo lsof -i :3000 

#Then run this, with <PID> replaced by the value in the column returned by previous command.
kill -9 <PID>

mac terminal find process by port

sudo lsof -i tcp:3000

what's running on port mac

lsof -i tcp:3000

running ports in mac

sudo lsof -PiTCP -sTCP:LISTEN

include script in html

<script type="text/javascript" src="/path/to/script.js"></script>