EspruinoRaffle.js

var interval = 50;

startRaffle = function() {
  [LED1, LED2, LED3].forEach(function(pin) {
    setInterval(function() {
      digitalWrite(pin, Math.random() > 0.5);
    }, interval);
  });
};

stopRaffle = function() {
  clearTimeout();
};

runRaffle = function() {
  s = !s;
  console.log("lights are " + (s ? "running" : "stopped"));
  if (s) {
    startRaffle();
  } else {
    stopRaffle();
  }
};

setWatch(runRaffle, BTN, {repeat: true, edge: "rising", debounce: 1});