if(obj) VS if(obj != null)

/**
 * Copyright and ( http://wonderfl.net/user/and )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/iB6P
 */

// forked from and's flash on 2015-4-29
package {
    import flash.events.TimerEvent;
    import flash.utils.Timer;
    import flash.text.TextField;
    import flash.display.Sprite;
    import flash.utils.getTimer;
    
    public class FlashTest extends Sprite {
        
        private var timer:Timer;
        private var tf:TextField;
        private var numIter:int = 100000000;
        private var step:int;
        
        public function FlashTest() {
            // write as3 code here..


            
            tf = new TextField();
            tf.textColor = 0xFF3333;
            tf.width = 200;
            tf.height = 600;
            tf.multiline = true;
            addChild(tf);
            var j:int = 3;
            if(j=2)
            {
                
            }

            
            var func : Function  = null;
            if(func)
            {
                tf.appendText("f1" + "\n\n");
            }
            else
            {
                tf.appendText("f2" + "\n\n");
            }
            

            step = 0;
            timer = new Timer(3000, 1);
            timer.addEventListener(TimerEvent.TIMER_COMPLETE, test);
            timer.start();

        }
        
        private function test(e:TimerEvent):void
        {
            var time:int;
            var i:int;
            var o:Object;
            var o1:Object = new Object();
            
            if(step == 0)
            {
                time = getTimer()
                for(i = 0; i<numIter; i++)
                {
                    if(o)
                    {
                        
                    }
            
                }
                tf.appendText("IF ObjNull: " + (getTimer() - time) + "\n\n");
                
            }
            else if(step == 1)
            {
                time = getTimer()
                for(i = 0; i<numIter; i++)
                {
                    if(o!=null)
                    {
                        
                    }
            
                }
                tf.appendText("ifNull ObjNull: " + (getTimer() - time) + "\n\n");
            }

            else if(step == 2)
            {
                time = getTimer()
                for(i = 0; i<numIter; i++)
                {
                    if(o1)
                    {
                        
                    }
            
                }
                tf.appendText("IF ObjNotNull: " + (getTimer() - time) + "\n\n");
            }
            else
            {
                time = getTimer()
                for(i = 0; i<numIter; i++)
                {
                    if(o1!=null)
                    {
                        
                    }
            
                }
                tf.appendText("ifNull ObjNotNull: " + (getTimer() - time) + "\n\n");
            }
           
           if(step < 3)
           {
               step++;
               timer.start();
           }

        }

    }
}