var Friends;
	var form;
	
	function $(element)
	{
		if(element)
		{
		return document.getElementById(element)
		}
	}

    function addEvent( obj, type, fn ) {
		if(obj)
		{
			if (obj.attachEvent) 
			{
		        obj.attachEvent( 'on'+type, fn );
      		} else
        		obj.addEventListener( type, fn,false); 	
		}	
     }

	

	
	
	
	function initFormEvent()
	{
		form = document.getElementById('formEvent');
		
		Friends = new Array($('friend1'),$('friend2'),$('friend3') )
		for(var i in Friends)
		{
			Friends[i].style.display = 'none';
		}	
		
		// Add event on Form.		
		addEvent($('friendSelect3') , 'click' ,function(){$('number-of-person').disabled=false;addEvent($('number-of-person') , 'change' ,function(){checkSelectNumberFriend()});checkSelectNumberFriend()});
		
		addEvent($('friendSelect1') , 'click' ,function(){$('number-of-person').disabled=true;hideAllFriends()});
		addEvent($('friendSelect2') , 'click' ,function(){$('number-of-person').disabled=true;hideAllFriends()});
		
		
		
	}
	
	function checkSelectNumberFriend()
	{	
		for (var i = 0 ; i <Friends.length ; i++)		
		{			
			if($('number-of-person').value>i)
			{
				Friends[i].style.display = 'block'
			}
			else
			{
				Friends[i].style.display = 'none'
			}			
		}
	}
	
	
	function hideAllFriends()
	{
		for (var i = 0 ; i <Friends.length ; i++)		
		{
			Friends[i].style.display = 'none'
		}		
	}