Node not responding in ubuntu?

I have installed nodejs on ubuntu.

username@username-VirtualBox:~$ cd node
username@username-VirtualBox:~/node$ node app.js

If I made a mistake in my code then it's respond me about the error but when my code is working code it's not respond me anything. Like people have shown that "running on 127.0.0.1230".

How I can got it worked.

Here is an app.js that will show running on 127.0.0.1230:

console.log( 'running on 127.0.0.1230' );

When you run it like this: node app.js, you get running on 127.0.0.1230.

console.log logs something to the console.