Util.js

Util = {};

Util.tweenTint = function(obj, startColor, endColor, time) {
    // create an object to tween with our step value at 0
    var colorBlend = {step: 0};

    // create the tween on this object and tween its step property to 100
    var colorTween = game.add.tween(colorBlend).to({step: 100}, time);
    
    // run the interpolateColor function every time the tween updates, feeding it the
    // updated value of our tween each time, and set the result as our tint
    colorTween.onUpdateCallback(function() {
      obj.tint = Phaser.Color.interpolateColor(startColor, endColor, 100, colorBlend.step);
    });
    
    // set the object to the start color straight away
    obj.tint = startColor;    
    
    // start the tween
    colorTween.start();

    obj.colorTween = colorTween;
}