Changes in Web MIDI API in Chrome in 2019
What to do to make sure your app will still work
If you’ve been playing with Web MIDI API recently you might have seen the new warning that appears every time you run navigator.requestMIDIAccess().
[Deprecation] Web MIDI will ask a permission to use even if the sysex is not specified in the MIDIOptions since M75, around June 2019. See https://www.chromestatus.com/feature/5138066234671104 for more details.
What is sysex?
Sysex is an abbreviation for System Exclusive Messages. These are special type of messages that let you configure your MIDI device. Some synthesizers accepts uses as a configuration protocol, it allows to configure them or upload the patches to their memory.
Such data is usually stored in files with .syx extension but you can also use JavaScript (or any other language) to programmatically write them to.
Because these operations are usually persistent and can reconfigure the device, Chrome was always asking user for permission to perform such actions. Now Chrome will explicitly require user to grant permissions even if we do not use sysex.
