listening

npm install listening --save

var listening = require('listening');
listening(8080, function(err, res) {
  // res will be true/false
});

Listening API follows server.listen API.

why

Why would we want to test for a listening server before starting our own server, can't we just try to .listen again later on?

The current answer for node 0.10.x is no you can't.

See the node.js issue.