time validation for text box

valid time in 24 hours format with no seconds

my textboxes have same name and id with array

i am alerting the text box value onblur.It shows only the first text box value

I want to alert for every text box if value is not a number
Code:
	<?php
	session_start();
	if (!$_SESSION['uname']) header("Location:login.php"); ?>
	<html><head><title>Attendance sheet</title>
	<link rel="stylesheet" href="att_style.css" type="text/css" >
	<script type="text/javascript">
	
	function IsNumber(strAlert)
	{
	
	//alert(strAlert);
	var txtb = document.getElementById('in_time[]').value;
	//for (var i = 0; i < txtb.length; i++) {
	//var txtv = txtb[i].value;
	alert(txtb);
	//}
	}
	
	</script>
	</head>
	<body>
	<?php
	$cnn = mysql_connect("localhost","root","");
	mysql_select_db("time_sheet",$cnn);
	
	$dbdate = mysql_query("SELECT start_mon,end_mon FROM admin");
	$dd = mysql_fetch_array($dbdate);
	
	$curmon = getdate();
	$nextmonth = $curmon['mon'] + 1;
	$start = "2012" . "-" . $curmon['mon'] ."-". $dd['start_mon'];
	$end =  "2012" . "-". $nextmonth ."-". $dd['end_mon'];
	$_SESSION['fromdate'] = $start;
	$_SESSION['todate'] = $end;
	
	$dateMonthYearArr = array();
	$fromDateTS = strtotime($start);
	$toDateTS = strtotime($end);
	
	for ($currentDateTS = $fromDateTS; $currentDateTS <= $toDateTS; $currentDateTS += (60 * 60 * 24)) {
	$currentDateStr = date("M d",$currentDateTS);
	$notmysql[] = $currentDateStr;
	
	$currmysql = date("Y-m-d",$currentDateTS);
	$mysqlfor[] = $currmysql;		
	}
	echo "	No of days: " . count($mysqlfor);
	//Table for view
	
	if (isset($_REQUEST['sub'])) {
	$inti = $_POST['in_time'];
	$outi = $_POST['out_time'];
	
	$intime = serialize($inti);
	$outtime = serialize($outi);
	
	$inser = unserialize($intime);
	$outser = unserialize($outtime);
	$dbdate = mysql_query("SELECT start_mon,end_mon FROM admin");
	$dd = mysql_fetch_array($dbdate);
	$curmon = getdate();
	$nextmonth = $curmon['mon'] + 1;
	
	$dateMonthYearArr = array();
	$fromDateTS = strtotime($start);
	$toDateTS = strtotime($end);
	
	for($b = 0; $b < count($mysqlfor); $b++) {
	$qry = mysql_query("SELECT * FROM timetable where date = '".$mysqlfor[$b]."' ");
	$ds = mysql_fetch_array($qry);
	
	if(!$qry) die(mysql_error());
	$check = mysql_num_rows($qry);
	//				print_r($inser);
	if($check == 0) {
	if($inser[$b] == "") $inser[$b] = '00:00';
	
	if($outser[$b] == "") $outser[$b] = '00:00';
	
	$ins = mysql_query("INSERT INTO timetable VALUES ('', '".$_SESSION['uname']."', 
	'".$mysqlfor[$b]."', '".$inser[$b]."', '".$outser[$b]."', '') ");
	}
	else {
	//print_r($mysqlfor[$b]);
	$upd = mysql_query("UPDATE `timetable` SET `in` = '".$inser[$b]."',
	 `out` = '".$outser[$b]."' WHERE `date` = '".$mysqlfor[$b]."' ");
	if(!$upd) die(mysql_error());					
	}
	}
	}
	?>
	<form name="myForm" method="post" action="">
	<table border="1" cellspacing="0" cellpadding="2">
	<tr><th scope="row">DATE</th>
	<?php
	for ($s = 0; $s < 10; $s++) {
	?>
	<td align="center"><?php print_r($notmysql[$s]); } ?></td></tr>
	
	<tr><th scope="row">IN</th> <?php 
	for ($ss = 0; $ss < 10; $ss++) { ///////////////getting from DB
	$sele = mysql_query("SELECT * FROM timetable where date = '".$mysqlfor[$ss]."' ");
	$emp = mysql_num_rows($sele);
	?>
	<td align="center"> <?php
	$numrows = mysql_num_rows($sele);
	if($numrows == 0) { 
	?>
	<input name="in_time[]" id="in_time[]" type="text" onBlur="IsNumber();" size="5">
	</td>
	<?php
	}
	else {
	while($row1 = mysql_fetch_array($sele))  {		
	?>
	<input name="in_time[]" id="in_time[]" type="text" onBlur="IsNumber();" 
	value="<?php echo $row1['in']; ?>" size="5"></td>
	<?php } 
	}
	}?>
	</tr>
	
	<tr><th scope="row">OUT</th> <?php 
	for ($v = 0; $v < 10; $v++) {
	?>
	<td align="center"> <?php
	$sel2 = mysql_query("SELECT * FROM timetable where date = '".$mysqlfor[$v]."'");
	$numrows = mysql_num_rows($sel2);
	if($numrows == 0) { ?>
	<input name="out_time[]" id="out_time[]" type="text" size="5"></td> 
	<?php 
	}
	else {
	while($row2 = mysql_fetch_array($sel2)) { ?>
	<input name="out_time[]" id="out_time[]" type="text" onBlur="IsNumber();" 
	value="<?php echo $row2['out']; ?>" size="5"></td>
	<?php
	}
	}
	}?>
	</tr>
	
	<tr><th scope="row">Late</th><?php for ($s = 0; $s < 10; $s++) { 
	?>
	<td align="center"><input name="late_time[]" id="late_time[]" onBlur="IsNumber();" 
	type="text" size="5"></td> 
	<?php  
	}?>
	</tr>
	</table>
	<br><br>
	<!-- second tab-->
	<?php if(count($notmysql) >= 11) { ?>
	<table border="1" cellspacing="0" cellpadding="2"><tr><th scope="row">DATE</th>
	<?php
	for ($st = 10; $st < 20; $st++) { ?>		
	<td align="center"><?php print_r($notmysql[$st]); ?></td>
	<?php	
	}
	?></tr>
	
	<tr><th scope="row">IN</th> 
	<?php for ($g = 10; $g < 20; $g++) { 
	$selec = mysql_query("SELECT * FROM timetable where date = '".$mysqlfor[$g]."'");
	$numrows = mysql_num_rows($selec);
	?> <td align="center"> <?php
	if($numrows == 0) { ?>	
	<input name="in_time[]" id="in_time[]" type="text" onBlur="IsNumber();" size="5"></td>
	<?php
	}
	else {
	while($secinrow = mysql_fetch_array($selec)) { ?>
	<input name="in_time[]" id="in_time[]" value="<?php echo $secinrow['in']; ?>" onBlur="IsNumber();"
	type="text" size="5"></td>
	<?php  
	}
	}
	}?></tr>
	
	<tr><th scope="row">OUT</th>
	<?php for ($h = 10; $h < 20; $h++) { 
	$select = mysql_query("SELECT * FROM timetable where date = '".$mysqlfor[$h]."'");
	?>
	<td align="center"> <?php
	$numrows = mysql_num_rows($select); 
	if($numrows == 0) {?>
	<input name="out_time[]" id="out_time[]" type="text" onBlur="IsNumber();" size="5"></td>
	<?php 
	}
	else { 
	while($secoutrow = mysql_fetch_array($select)) {
	?> 
	<input name="out_time[]" id="out_time[]" type="text" onBlur="IsNumber();" 
	value="<?php echo $secoutrow['out']; ?>" size="5"></td>
	<?php } 
	}
	}?></tr>
	
	<tr><th scope="row">Late</th>
	<?php for ($m = 10; $m < 20; $m++) { ?>
	<td align="center"><input name="late_time[]" id="out_time[]" onBlur="IsNumber();"
	type="text" size="5"></td> <?php 
	} 
	?>
	</tr>
	</table>
	<?php } ?> 
	<br/><br/>
	
	<!-- Third table-->
	<?php if(count($notmysql) >= 21) { ?>
	<table border="1" cellspacing="0" cellpadding="2">
	<tr>
	<th scope="row">DATE</th>
	<?php
	for ($tt = 20; $tt < count($notmysql); $tt++) { 	
	?>
	<td align="center"><?php print_r($notmysql[$tt]); ?></td><?php } 
	?>
	</tr>
	
	<tr><th scope="row">IN</th>
	<?php for ($j = 20; $j < count($notmysql); $j++) {
	$selected = mysql_query("SELECT * FROM timetable where date = '".$mysqlfor[$j]."' ");
	?> <td align="center"> <?php
	$numrows = mysql_num_rows($selected);
	if($numrows == 0) {?>
	<input name="in_time[]" id="in_time[]" type="text" onBlur="IsNumber();" size="5"></td>
	<?php }
	else {
	while($treinrow = mysql_fetch_array($selected)) {
	?>
	<input name="in_time[]" id="in_time[]" type="text" onBlur="IsNumber();"
	value="<?php echo $treinrow['in']; ?>" size="5"></td> 
	<?php
	}
	}
	}
	?>
	</tr>
	
	<tr><th scope="row">OUT</th> <?php for ($k = 20; $k < count($notmysql); $k++) { 
	$selectedr = mysql_query("SELECT * FROM timetable where date = '".$mysqlfor[$k]."'");
	$numrows = mysql_num_rows($selectedr);
	?>
	<td align="center"> <?php	
	if($numrows == 0) { ?>	
	<input name="out_time[]" id="out_time[]" type="text" onBlur="IsNumber();" size="5"></td> 
	<?php }
	else {
	while($treoutrow = mysql_fetch_array($selectedr)) {
	?>	
	<input name="out_time[]" id="out_time[]" onBlur="IsNumber();" 
	value="<?php echo $treoutrow['out']; ?>" type="text" size="5"></td> 
	<?php 
	}
	}
	} ?>
	</tr>
	
	<tr><th scope="row">Late</th>
	<?php for ($s = 20; $s < count($notmysql); $s++) { ?>
	<td align="center">
	<input name="late_times[]" id="late_times[]" type="text" value="<?php ?>" size="5"></td> <?php 
	} ?>
	</tr>
	</table>
	<?php } ?>
	<!--Table End -->
	<a style="float:right" href="logout.php">Logout</a>
	<p align="center"><input name="sub" type="submit" value="Save"></p>
	</form>
	</body>
	</html>