How do I turn on logging in the Firebase Javascript client?

In the 3.0.0 version of Firebase, this has been changed to:

firebase.database.enableLogging(true);

See enableLoggging documentation.

To turn on logging, you can call:

Firebase.enableLogging(true);

And it'll log to the console. This logging is mostly meant for internal debugging purposes though; it's not super user-friendly. But hopefully it'll help.

If you want to capture the messages programmatically instead of send them directly to the console, you can alternatively pass a function to enableLogging:

Firebase.enableLogging(function(logMessage) {
  // Add a timestamp to the messages.
  console.log(new Date().toISOString() + ': ' + logMessage);
});