How to fix Error: listen EADDRINUSE while using nodejs?

Question

If I run a server with the port 80, and I try to use xmlHTTPrequest i get this error: Error: listen EADDRINUSE

Why is it problem for nodejs, if I want t

Answer 1

lsof -i:3000;
kill -9 $(lsof -t -i:3000);
// 3000 is a your port
// This "lsof -i:3000;" command will show PID 
kill PID 
ex: kill 129393