รบกวนดูโค้ด เช็คไฟล์ extension ให้หน่อยครับ ^___________^

<!--Add -->
<? if($_GET['action']=='add'){?>
<!--Check type file & over file -->
<script language="javascript">
limitFileSize = 1024;//byte
fileSize = 0;
//binds to onchange event of your input field
$().ready(function(){
		$('#fileUpload').bind('change', function() {
			fileSize = this.files[0].size;
			
			if(fileSize>limitFileSize){
			alert("File over size Allow 200 Kb");
			return false;
			}
	    	//alert(fileSize);
		});
	}
);
function check_extension(eID) {
	file = document.getElementById(eID).value;
	var temp=file.split(".");
	var type = temp[temp.length-1];
	//alert(type);
	//extension[ext]
	if (type=='png'|| type=='gif'|| type=='jpg'|| type=='jpeg'|| type=='PNG'|| type=='GIF'|| type=='JPG'|| type=='JPEG'){ 
		//alert ('file ok') ; 
		return true;
	} else { 
		return false;
	}
}
function fncSubmit()
{
	if(document.form_add.fileUpload.value == "")
	{
		alert('Please enter image .png .gif .jpg .jpeg .PNG .GIF .JPG .JPEG only');
		document.form_add.fileUpload.focus();
		return false;
	}
	
	if(document.form_add.fileUpload.value != ""){
		correct =  check_extension("fileUpload");
		if(!correct){
			alert("file type was incorrect");
			return false;
		}
	}
</script> 
<form action="" method="post" name="form_add" target="_parent" onSubmit="JavaScript:return fncSubmit();" enctype="multipart/form-data"> 
<ul class="showInColumn_add">
	<li><u>Add</u></li>
    <li>Title :<input name="txt_title" type="text" size="50" /></li>
    <li>Detail :</li><br />
    <li><textarea name="txt_detail" cols="36" rows="5"></textarea></li>
    <li><input name="fileUpload" id="fileUpload" type="file" size="37px" /><font color="#FF0000">*.jpg only</font></li>
    <li><input name="save" type="submit" value="Save" /></li>
</ul>
<?
$date_today=date("Y-m-d");	
	if(isset($_POST['txt_title']))
		{
	if(move_uploaded_file($_FILES["fileUpload"]["tmp_name"],"../uploads/3m/".time()."_".$_FILES["fileUpload"]["name"])) // Upload/Copy
	{
		echo "Upload Complete.";
	}//file
$sql="INSERT INTO tb_3m_insulating(title,detail,images,date_today)VALUES('$_POST[txt_title]','$_POST[txt_detail]','".time()."_".$_FILES["fileUpload"]["name"]."','$date_today')";
	$q=mysql_query($sql)or die (mysql_error());
	if($q){
			redirect('3m_insulating.php');
		}else{
			alert('Can\'t insert');
		}
	//echo $sql;
	}//if
?>
</form>
<? } ?>