stop port if running using shell schript code example

Example 1: kill app at port

#To list any process listening to the port 8080:
lsof -i:8080

#To kill any process listening to the port 8080:
kill $(lsof -t -i:8080)

#or more violently:
kill -9 $(lsof -t -i:8080)

Example 2: kill a port

kill $(lsof -ti:3000)