Espruino fade in and out script with light string (individual addressable lights)

fade.js

// change this if you use another port or if your lights work with 32 instead of 64 baud
SPI1.setup({baud:6400000, mosi:A7});

var rgb = new Uint8Array(25*3); // 25 x RGB lights

// turn off board leds
digitalWrite(LED1,0);
digitalWrite(LED2,0);
digitalWrite(LED3,0);

var numOfLights = 25;

// turn them all off
function off() {
  var n = 0;
  for (var i=0;i<numOfLights;i++) {
    rgb[n++] = 0;
    rgb[n++] = 0;
    rgb[n++] = 0;
  }
  doLights();
}

// slowly fade in and out different random color each time
var direction = -1;
var pos = 0;
var r,g,b;
function flow() {
  if (pos > 255 || pos < 1) {
    direction *= -1;
  }
  if (pos < 1) {
    r = Math.floor(Math.random() * 255);
    g = Math.floor(Math.random() * 255);
    b = Math.floor(Math.random() * 255);
    console.log(r,g,b,direction,pos);
  }
  var n = 0;
  for (var i = 0; i < numOfLights; i++) {
    rgb[n++] = Math.ceil((Math.sin(pos/255)*r));
    rgb[n++] = Math.ceil((Math.sin(pos/255)*g));
    rgb[n++] = Math.ceil((Math.sin(pos/255)*b));
  }
  pos += direction;
  doLights();
}

function doLights() {
  SPI1.send4bit(rgb, 0b0001, 0b0011);
}

off();
setInterval(flow, 20);