How to play audio randomly - Appcelerator Titanium

app.js

var win = Ti.UI.createWindow({
	backgroundColor : '#000',
	layout:'vertical'
 
 });
 
var mp3_array = [];
mp3_array.push('music/sound1.mp3');
mp3_array.push('music/sound2.mp3');
mp3_array.push('music/sound3.mp3');
 
Titanium.Media.audioSessionMode = Titanium.Media.AUDIO_SESSION_MODE_AMBIENT;
 
var current_index = 0;
 
function playSound(index){
    var sound = Titanium.Media.createSound();    
    sound.url = mp3_array[index];
    sound.play();
 
    Ti.API.info('Now Playing '+index+': '+mp3_array[index]);
    
    sound.addEventListener('complete',function(){
        current_index++;
        if(current_index < mp3_array.length){
            playSound(current_index);
        }
        else {
        	Ti.API.info('all sounds complete!');
        }
     });
}
playSound(current_index);

win.open();