Answers for "What attribute of the script tag is used for adding the external JavaScript file?"

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>

kill process running on port mac

sudo lsof -i :3000

kill -9 <PID>

kill port mac terminal

sudo lsof -i <Port>
sudo kill -9 <PID>

import js in html

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

linking a script .js

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