stringのindexOfの挙動を確認する

/**
 * Copyright mmlemon_ ( http://wonderfl.net/user/mmlemon_ )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/g4Fm
 */

package {
    import flash.display.Sprite;
    import flash.text.*;
    public class FlashTest extends Sprite {
        
        private var tf:TextField;
        public function FlashTest() {
            // write as3 code here..
            
            init();
        }
        private function init():void
        {
            tf = new TextField();
            addChild(tf);
            var ext:String = ".html";
            var str:String = "sample.html?jklsjkrl#jsjkrl";
            var index:int = str.indexOf(ext);
            tf.text = index.toString();
            // .html以降の文字列を削除したものを取得
            var ans:String = str.substr(0, index + ext.length);
            tf.appendText(" " + ans);
        }
    }
}