คำนวณวันที่ 2 ช่วง ยังไงให้แสดงผลทันที ในหน้าเดียวกัน

<script type="text/javascript">
function TimeDriff()
{
	var diff;
	var start_val = document.getElementById('start').value;
	var end_val = document.getElementById('end').value;
	var start = start_val.split("\/");
	var end = end_val.split("\/");

	//if use thai year
	start[2] -= 543;  
	end[2] -= 543; 
	
	StratDate = new Date(start[2],start[1]-1,start[0]); 
	EndDate = new Date(end[2],end[1]-1,end[0]);  	
	
	if(StratDate.getTime( ) < EndDate.getTime( ))
	{  
		diff = Math.round((EndDate - StratDate)/86400000);
	 }
	else if(EndDate.getTime( ) < StratDate.getTime( ))
	{
		diff = "0";
	}
	else if(EndDate.getTime( ) == StratDate.getTime( ))
	{
		diff = "0";
	}

	if(diff==undefined)
		document.getElementById("tmdiff").value = "";
	else
		document.getElementById("tmdiff").value = diff;
}
</script>

<b>Calculate Time Between </b><p>
<table border="1" cellspacing="0" cellpadding="2">
<tr><td>Time Start : </td><td><input type="text" id="start" name="start" onblur="TimeDriff()"></td></tr>
<tr><td>Time End : </td><td><input type="text" id="end" name="end" onblur="TimeDriff()"></td></tr>
<tr><td>Time Diff : </td><td><input type="text" id="tmdiff" name="diff"> Days</td></tr>
</table>