APC20 MIDI controller Hydra script

hydra_apc20.js

navigator.requestMIDIAccess()
    .then(onMIDISuccess, onMIDIFailure);

function onMIDISuccess(midiAccess) {
    console.log(midiAccess);
    var inputs = midiAccess.inputs;
    var outputs = midiAccess.outputs;
    for (var input of midiAccess.inputs.values()){
        input.onmidimessage = getMIDIMessage;
    }
}

function onMIDIFailure() {
    console.log('Could not access your MIDI devices.');
}

var cc=Array(256).fill(0.5).map(x => Array(256).fill(0.5));

getMIDIMessage = function(midiMessage) {
    var arr = midiMessage.data;    
    var index_a = arr[0];
    var index_b = arr[1];
    var val = (arr[2]+1)/128.0;
    console.log('Midi received on cc' + index_a + ' ,' + index_b + ' value:' + val);
    cc[index_a][index_b] = val;
};