WittyEspruino.js

var shhh = "SECRETPASSWORD";

function hexToRgb(hex) {
  // No RegEx in Espruino yet...
  var R, G, B;
  if (hex.length == 3) {
    R = hex.substring(0, 1);
    R = R + R;
    G = hex.substring(1, 2);
    G = G + G;
    B = hex.substring(2, 3);
    B = B + B;
  } else {
    R = hex.substring(0, 2);
    G = hex.substring(2, 4);
    B = hex.substring(4, 6);
  }

  return {
    R: parseInt(R, 16),
    G: parseInt(G, 16),
    B: parseInt(B, 16)
   };
}




// Usage
//E.on('init', function() {
  var server = "192.168.128.62";
  var mqtt = require("MQTT").create(server);
  var wifi = require("Wifi");
  function Witty() {
    var self = this;
    this.colorIntervalId = null;
    this.colorDuration = 1000;
    this.PIN_LDR = 0;
    this.PIN_BUTTON = 4;
    this.PIN_LED_R = 15;
    this.PIN_LED_G = 12;
    this.PIN_LED_B = 13;

    this.buttonActions = [];

    this._btnWatch = setWatch(
      function(evt) {
        for (var i = 0; i < self.buttonActions.length; i++) {
          self.buttonActions[i].apply(self, [evt]);
        }
      },
      this.PIN_BUTTON,
      {repeat: true, edge: 'rising'}
    );
    // TODO:csd - Not working
    this._ldrWatch = setWatch(
      function(evt) {
        console.log("LDR", evt);
      },
      this.PIN_LDR,
      {repeat:true}
    );
  }

  Witty.prototype.addButtonAction = function(fn) {
    this.buttonActions.push(fn); 
  };

  Witty.prototype.getPhotoResistance = function() {
    return analogRead(0);
  };



  Witty.prototype.setLED = function(hex) {
      console.log("Setting LED", hex);
      var result = hexToRgb(hex);
      console.log("Which is", result);
      digitalWrite(this.PIN_LED_R, result.R);
      digitalWrite(this.PIN_LED_G, result.G);
      digitalWrite(this.PIN_LED_B, result.B);
  };

  Witty.prototype.setLEDTheme = function(colors) {
    var self = this;
    self.stopLEDTheme();
    var index = 0;
    this.setLED(colors[index]);
    this.colorIntervalId = setInterval(function() {
      index++;
      if (index >= colors.length) {
        index = 0;
      }
      self.setLED(colors[index]);
    }, this.colorDuration);
  };

  Witty.prototype.stopLEDTheme = function(colors) {
    if (this.colorIntervalId) {
      clearInterval(this.colorIntervalId);
      this.colorIntervalId = null;
    }
  };

  var witty = new Witty();
  witty.addButtonAction(function(evt) {
    console.log("Button pressed", evt.state, evt.time, evt.lastTime);
    console.log("Photo resistance is", witty.getPhotoResistance());
    witty.stopLEDTheme();
  });

  witty.setLED("0f0");

  


  wifi.connect("YourAccessPointName", {password: shhh}, function(err) {
    if (err) throw err;
    console.log("Wifi connected");
    mqtt.connect();
  });

  mqtt.on('connected', function() {
    console.log("mqtt connected");
    mqtt.subscribe("witty");
  });

  mqtt.on('publish', function(pub) {
    console.log("Topic:" + pub.topic);
    console.log("Message:" + pub.message);
    var message = JSON.parse(pub.message);
    if (!message.colors || message.colors.length === 0) {
      witty.stopLEDTheme();
      return;
    }
    message.colors.push("000");
    witty.setLEDTheme(message.colors);
  });
//});

Thanks @craigsdennis it's working perfectly!! Do you know how to access the GPIO pins?