close a port with nodeJS

Question

As I write a program that listen on a port, lets say 8081, and then write another program that listen on the same port I will get this type of error message:

Error: listen EADDRINUSE
    at errnoException (net.js:901:11)
    at Server._listen2 (net.js:1039:14)
    at listen (net.js:1061:10)
    at Server.listen (net.js:1127:5)
    at Object.<anonymous> (C:\NetBeansWorkPlace\nodeJS_Files\TutsNodeJS\static_file_server.js:36:4)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)

I found that the port is in use but how can I clear the port, or stop the app from listening on a given port?

Answer 1

Simplest approach is you can change the port number in your javascript file.

If you want to close the port simply do this (solution is for mac) open terminal

1) sudo lsof -i :

a table will be displayed look for PID in this table for your port

2) sudo kill -9 PID

Answer 2

If you want that your node app will automatically close port 8081 before it's further processes start, you can use this trick.

1. Install the dependency :npm i kill-port

2. Now, import and run the code given below.

const kill = require("kill-port");

kill(8080, "tcp");

With this, node will first clear the port connection at first so that you can go further with this port. And if the port is not open, then it will cause no harm.