Programmatically stop and restart express servers (to change ports)

node.js express ports

Matt · Mar 31, 2012 · Viewed 55.5k times · Source

I'm looking to be able to basically change ports that my express app is running on.

I've tried:

server.on('close', function() {
  server.listen(3000);
});

server.listen(8080);
server.close();

This returns a cryptic node.js error. I'm running node v0.4.11, I'm upgrading now to see if that fixes it.

EDIT Here's the error:

Assertion failed: (!io->watcher_.active), function Set, file ../src/node_io_watcher.cc, line 160.

Thanks, Matt

Answer

The issue is that .listen is asynchronous. By calling .close immediately after calling .listen, you are closing it before it has been opened.

Try this instead.

server.listen(8080, function() {
  server.close();
});