nth-child test

/**
 * Copyright grapefrukt ( http://wonderfl.net/user/grapefrukt )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/9ZK6
 */

// forked from grapefrukt's flash on 2011-6-3
package {
    import flash.display.Sprite;
    import flash.text.TextField;
    import flash.text.TextFormat;
    import flash.events.Event;
    
    import com.bit101.components.NumericStepper;
     
    public class FlashTest extends Sprite {
        
        private var tf:TextField; 
        private var ns_a:NumericStepper;
        private var ns_b:NumericStepper;

        public function FlashTest() {
            
            tf = new TextField();
            tf.defaultTextFormat = new TextFormat("_sans");
            tf.height = 500;
            tf.width = 500;
            tf.x = 10;
            tf.y = 30;
            tf.selectable = false;
            addChild(tf);           
           
            
            ns_a = new NumericStepper(this, 10, 10, redraw);
            ns_b = new NumericStepper(this, 100, 10, redraw);
           
           redraw();
        }
        
        public function redraw(e:Event = null):void {
            tf.text = "";
            for ( var i:int = 0; i < 40; i++){
                trace(i + ":\t" + isNth(i, ns_a.value, ns_b.value));
            }
        }
        
        public function isNth(index:int, a:int, b:int):Boolean {
            return a < 0 ? (index - b < 0 && !((index - b) % a == 0)) : (index - b >= 0 && (index - b) % a == 0);
        }
        
        public function trace(t:*):void{
            tf.appendText(t + "\n");
        }
    }
}