What are the numbers in the [j] array?

[lukeacat]

Are they notes? I'm trying to make a thing that'll need keys like G2, and such.

        var data = require('fs').readFileSync('midi/149.mid', 'binary');
        var smf = new JZZ.MIDI.SMF(data);

        for (var i = 0; i < smf.length; i++) {
            for (var j = 0; j < smf[i].length; j++) {
                setTimeout(e=>{
                }, smf[i][j].tt)
              //console.log('track:', i, 'tick:', smf[i][j].tt);
              // or do whatever else with the message
            }
          }

This is what I've gotten so far.

[jazz-soft]

Those are MIDI messages (including noteOn/noteOff) and meta events.
You can get a better idea if you look inside the SMF.toString() function.