Is there a way to check if the send() method has sent all the data in the queue and use some kind of event handler? Maybe check if the queue is empty or not?

I have an application that sends a 64 patch SYSEX dump to Roland D-50 and want to know when the SYSEX is sent. In this case I have a workaround using Javascript

setTimeout(function(){console.log("SYSEX sent");}, 12000);

This kind of SYSEX always takes 12 seconds to send. But this is not optimal.