flow.js

var keyboard = require('msi-keyboard');
var colors = ['red','yellow','green','sky','blue','purple'];

var reg1 = 0;
var reg2 = 1;
var reg3 = 2;

keyboard.color('left', colors[reg1]);
keyboard.color('middle', colors[reg2]);
keyboard.color('right', colors[reg3]);
keyboard.mode('normal');

setInterval(function(){
    keyboard.color('left', colors[reg1]);
    keyboard.color('middle', colors[reg2]);
    keyboard.color('right', colors[reg3]);
    reg1+=1;
    reg2+=1;
    reg3+=1;
    if (reg1>5) { reg1=0; }
    if (reg2>5) { reg2=0; }
    if (reg3>5) { reg3=0; }
}, 1000);