I would like a simple JavaScript command or commands to send a System Exclusive File (.syx) to synthesizer via a MIDI controller. I am helping a musician friend and not sure I am able to go through the long process of learning all midi commands just for this one task.

My guess is that this request makes sense as it stands to a JavaScript expert who understands midi commands. Hopefully, the command is generic enough that details are not important. However, if that guess is wrong, the details are as follows:
He wants to send to a Roland MKS-50 synthesizer through a FocusRite MIDI controller. He normally uses either the SNOIZE (Mac) or SYSXLIB.exe (Win) program for communication but neither will work for our task.

Specifically, the one task: The Roland file ‘MKS0rig.mid’ is potentially useful but unusable for many musicians (forums have complaints from many people). We read the file with JavaScript and break it into five parts. We intend to send these parts individually as .sys files with on screen instructions on which synthesizer buttons to push and when. Everything is in place except for the command to the MIDI controller to send the individual ‘system exclusive files’ (which are JavaScript binary strings).