simpleMelody.js

const scribble = require('scribbletune');
const chords = scribble.getChordsByProgression('C4 minor', 'ii III ii v'); //i III ii v
const notes = [];
let pattern = '';

chords.split(' ').forEach((c, i) => { 
  const chord = scribble.chord(c);
  if (i % 2 !== 0) {
    // use 2 quarter notes
    notes.push(chord[0]);
    notes.push(chord[1]);
    pattern = pattern + 'xx'
  } else {
    // use a quarter note and 2 eigth notes
    notes.push(chord[0]);
    notes.push(chord[1]);
    notes.push(chord[2]);
    pattern = pattern + 'x[xx]'
  }
});

const clip1 = scribble.clip({
  notes,
  pattern: pattern
});

const clip2 = scribble.clip({
  notes,
  pattern: pattern,
  subdiv: '2n'
});


scribble.midi(clip1, 'clip1.mid');
scribble.midi(clip2, 'clip2.mid');