[PHP]สอบถามการคำนวณหาค่าความต่างของเวลา นำมาใช้กับ textbox

function dateDiv($t1,$t2){

  $t1Arr=splitTime($t1);
  $t2Arr=splitTime($t2);
 
  $Time1=mktime($t1Arr["h"], $t1Arr["m"]);
  $Time2=mktime($t2Arr["h"], $t2Arr["m"]);
 $TimeDiv=abs($Time2-$Time1);

  $Time["H"]=intval(($TimeDiv%86400)/3600); 
  $Time["M"]=intval((($TimeDiv%86400)%3600)/60); 
 return $Time;
}

function splitTime($time){
$timeArr["h"]= substr($time,0,2);
$timeArr["m"]= substr($time,3,2);
return $timeArr;
}

$t1= $_POST['box1'];
$t2= $_POST['box2'];
$rest = "";
if ($t2<$t1){
	$t2 = "24:00";
	$time=dateDiv($t1,$t2);
	$rest = implode(":",$time);
}else if ($t2>$t1) {
	$time=dateDiv($t1,$t2);
	$rest = implode(":",$time);
}

echo "<script>
$(function(){
$('#box3').val('$rest');
});
</script>";

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<div id="res"></div>
<input type="text" name="box1" id="box1" class="cal" />
<input type="text" name="box2" id="box2" class="cal" />
<input type="text" name="box3" id="box3" />
<script>
$(function(){
$(".cal").keyup(function(){
var box1 = $("#box1").val();
var box2 = $("#box2").val();
$.post('act.php',{'box1':box1,'box2':box2},function(data){
$("#res").html(data);
});
});
});
</script>