Kineticjs fillAlpha not working

Can anybody tell me or put me on the right way regarding the following problem? I want to create textbox on canvas using kineticjs. I am trying to get a text with transparent fill and with black stroke. It seems canvas is not doing anything when I try either of the following two:

obj.setAttr('fillAlpha',0.1); - nothing happens
obj.fillAlpha(0.1); - throws an error on canvas: Uncaught TypeError: Object # has no method 'fillAlpha'

Solution

To independently adjust fill opacity and stroke opacity, you need to create a group containing a stroked text object and a filled text object.

Here's example code and a Demo: http://jsfiddle.net/m1erickson/b7qAB/

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Prototype</title>
    <script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
    <script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v5.0.1.min.js"></script>
<style>
body{padding:20px;}
#container{
  border:solid 1px #ccc;
  margin-top: 10px;
  width:350px;
  height:350px;
}
</style>        
<script>
$(function(){

    var stage = new Kinetic.Stage({
        container: 'container',
        width: 350,
        height: 350
    });
    var layer = new Kinetic.Layer();
    stage.add(layer);

    var textGroup=new Kinetic.Group({
        x:10,
        y:30,
        draggable: true
    });
    layer.add(textGroup);

    var textFill = new Kinetic.Text({
        x:0,
        y:0,
        text:"Hello",
        fontSize:108,
        fill: 'red'
    });
    textGroup.add(textFill);

    var textStroke = new Kinetic.Text({
        x:0,
        y:0,
        text:"Hello",
        fontSize:108,
        stroke: 'black',
        strokeWidth: 3,
    });
    textGroup.add(textStroke);

    layer.draw();


    var strokeOpacity=1.00;
    var fillOpacity=1.00;
    var mode=1;
    var opacity=100;
    var delta=-1

    animate();

    function animate(){
        requestAnimationFrame(animate);

        if(opacity<1){
            delta=1; 
            opacity=1;
        }
        else if(opacity>100){
            opacity=100; 
            delta=-1; 
            mode=-mode;
        }
        else {
            opacity+=delta;
            if(mode==1){
                textStroke.setOpacity(opacity/100);
            }else{
                textFill.setOpacity(opacity/100);
            }
        }
        layer.draw();
    }

}); // end $(function(){});

</script>       
</head>
<body>
    <div id="container"></div>
</body>
</html>