Put Delay Before 'return' in Function

Question

When I create function that allow flash to detect object's velocity, a problem happen. I can't put delay before 'return' executed. It's cause result of function is null or 0. There's the script:
function SSvelocity(Target:Object,target_property:String,delay_ms:int=1000):Number
     if ((target_property!="x")&&(target_property!="y")&&(target_property!="z")&&(target_property!="rotation"))
          trace("ShortenScript: err(SSvelocity[1]): SSvelocity("+Target+","+target_property+","+delay_ms+")");
          trace("                                   SSvelocity(the_object,target_property,delay_millisecond)");
          trace("                                   position should filled with \"x\" or \"y\" or \"z\" or \"rotation\"");
          trace("                                   and don\'t forget about quotes(\")");
          DisplayError = true;
          return null;
     var detecta:Timer = new Timer(1000);
     var detectb:Timer = new Timer(1000);
     var resulta:Number;
     var resultb:Number;
     detecta.delay = delay_ms;
     detectb.delay = delay_ms;
     detecta.start();
     detecta.addEventListener(TimerEvent.TIMER, handlera);
     detectb.addEventListener(TimerEvent.TIMER, handlerb);
     function handlera(event:TimerEvent)
          detecta.stop();
          if (target_property == "x")
               resulta = Target.x;
          else if (target_property=="y")
               resulta = Target.y;
          else if (target_property=="z")
               resulta = Target.z;
          else if (target_property=="rotation")
               resulta = Target.rotation;
          detectb.start();
     function handlerb(event:TimerEvent)
          detectb.stop();
          if (target_property == "x")
               resultb = Target.x;
          else if (target_property=="y")
               resultb = Target.y;
          else if (target_property=="z")
               resultb = Target.z;
          else if (target_property=="rotation")
               resultb = Target.rotation;
     // I want put delay before return, because it's resulting NaN and often 0
     return (resultb-resulta);

Answer 1

I agree with Ned that you should rethink your approach. Objects A and B are your Information Experts (GRASP (object-oriented design) - Wikipedia, the free encyclopedia) on the problem at hand, so they should be responsible for storing their own previous positions and calculating velocity.
Let's assume that it's possible for you to apply the same Base Class to both A and B. That Base Class might look something like this:
public class VelocityClip extends MovieClip {
     //each history will contain the past 10 values for that property
     protected var propertiesHistory:Dictionary = new Dictionary();
     //by adding or removing property names to this Array, you can change what properties are being tracked
     protected var trackedProperties:Array = ['x', 'y', 'rotation'];
     //capture values every 100 ms (10 times a sec)
     protected var timer:Timer = new Timer(100);
     public function VelocityClip() {
          super();
          for each (var property:String in trackedProperties) {
               //create a spot to store the history of each tracked property
               propertiesHistory[property] = new Vector.<Number>();
          timer.addEventListener(TimerEvent.TIMER, storeValues);
          timer.start();
     protected function storeValues(e:TimerEvent):void {
          for each (var property:String in properties) {
               var history:Vector.<Number> = propertiesHistory[property] as Vector<Number>;
               if (history.length > 9) {
                    //stay at 10 total indices by removing first item
                    history.shift();
               history.push(Number(this[property]));
     public function getVelocity(property:String):Number {
          var history:Vector.<Number> = propertiesHistory[property] as Vector<Number>;
          if (!history) return NaN;//no history for this property
          if (history.length < 10) return 0; //haven't been moving for a full sec.
          //history[9] was recorded sometime in the last 99 ms, and history[9] and history[0] are 1 sec apart
          //subject to the limitations of the Timer Class
          return history[9] - history[0];