Looping vibration

Is there anyway to loop vibration ? I looked around API doc but could not find it. Then I tried to make a looping logic as below. But it did not work and ended up with infinite loop.... I would appreciate your advice on how to enable loop vibration.

looping part

do{
    Titanium.Media.vibrate();
}while(button.flag=="2");
 
button.flag = "0"   
        button.addEventListener('click', function(){
 
            if(button.flag=="1"){
                stopcountdown();
            }
 
            else if(button.flag=="0"){
                startcountdown();
                button.title = "Stop";      
            }
 
            else if(button.flag=="2"){
                resetcountdown();
                label.text = "Select timer";
                button.title = "Stopped";   
            }

entire code

button5min.addEventListener('click', function(){
            usersetTime =  5 * 60;
            label.text ="5:00";
            durationTime = 0; //????????,????0
            currentTime = usersetTime - durationTime;
            button.title = "Start";
        })
 
        button10min.addEventListener('click', function(){
            usersetTime =  10 * 60;
            label.text ="10:00";
            durationTime = 0; //????????,????0
            currentTime = usersetTime - durationTime;
            button.title = "Start";
        })
 
        button15min.addEventListener('click', function(){
            usersetTime =  15 * 60;
            label.text ="15:00";
            durationTime = 0; //????????,????0
            currentTime = usersetTime - durationTime;
            button.title = "Start";
        })
 
        button30min.addEventListener('click', function(){
            usersetTime =  30 * 60;
            label.text ="30:00";
            durationTime = 0; //????????,????0
            currentTime = usersetTime - durationTime;
            button.title = "Start";
        })
 
        button60min.addEventListener('click', function(){
            usersetTime =  60 * 60;
            label.text ="60:00";
            durationTime = 0; //????????,????0
            currentTime = usersetTime - durationTime;
            button.title = "Start";
        })
 
        button90min.addEventListener('click', function(){
            usersetTime =  90 * 60;
            label.text ="90:00";
            button.title = "Start";
            durationTime = 0; //????????,????0
            currentTime = usersetTime - durationTime;
            var button;
            button.title = "Start";
        })
 
        var setminute = 0.1;
        var usersetTime =  setminute * 60; 
        var durationTime = 0; 
        var currentTime = usersetTime - durationTime;   
        var timer;
        var sound = Ti.Media.createSound({url:"el_alarm.mp3"});
 
        function countdown(){   
                        if(currentTime>0){
                            durationTime = durationTime + 1;
                            currentTime = usersetTime - durationTime;
                            var minute = Math.floor(currentTime/60);
                            var sec = Math.floor(currentTime - minute*60);
                            label.text = minute + ":" + ("0" + sec).slice(-2);
                        }
                        else{
                            stopcountdown();
                            sound.looping = true;
                            sound.play();
                            label.text = "Wake up !";
                            button.title="OK";
                            do{
                                Titanium.Media.vibrate();
                            }while(button.flag=="2");
                        }                   
        }
 
        function startcountdown(){
            timer = setInterval(countdown, 1000);
            button.title="Stop";
            button.flag="1";
        }
 
        function stopcountdown(){
            clearInterval(timer);
            button.title = "Start";
            button.flag="2";
        }
 
        function resetcountdown(){
            sound.stop();
            button.flag="0";
        }
 
 
        // flag 0=??????????1=????????, 2=???????
 
        button.flag = "0"   
        button.addEventListener('click', function(){
 
            if(button.flag=="1"){
                stopcountdown();
            }
 
            else if(button.flag=="0"){
                startcountdown();
                button.title = "Stop";      
            }
 
            else if(button.flag=="2"){
                resetcountdown();
                label.text = "Select timer";
                button.title = "Stopped";   
            }
 
        });
 
        var service = Titanium.App.iOS.registerBackgroundService({
            url:'bkcountdown.js'        
        });
 
 
    return tab;
    };

in a Loop a condition needs to Change to have Chance that it will end sometime. Your condition is never changed (flag==2) therefore you have infinite Loop. You may try some sort of recursive function using setTimeout or setInterval.