ถามเรื่อง Java Script เช็ค Form ผมทำหน้า upload รูป โดยให้ upload 3 รูปโดยแต่ระรูป จะให้กรอก ชื่อรูป รายละเอียดรูป

<form enctype="multipart/form-data" method="post" action="fnupload.php">
<script type="text/javascript">

	        function check_data()
             { 		
		      // check type of file
		       if(document.getElementById('picture[]').value != "")
		        {		  
		           var typeFile = document.getElementById('picture[]').value.split('.');
		           typeFile = typeFile[typeFile.length-1];
		  
		            if(typeFile != "jpg" && typeFile != "jpeg")
		            {
		              alert("Extention of file invalid!!!.\nCan upload .jpg only \nPlease select file again.");
			          document.getElementById('picture[]').focus();
			          return false; 
		  
		            }else{
		  
		              return true;
		            }
		
		        }
				
			   // check photo name
			   if(document.getElementById('photo_name[]').value == "")
               {
			     alert("Please enter Photo Name.");
                 document.getElementById('photo_name[]').focus();
                 return false;
		       }
			   //check photo desc
			   if(document.getElementById('photo_desc[]').value == "")
               {
			     alert("Please enter Photo Description.");
                 document.getElementById('photo_desc[]').focus();
                 return false;
		       }
				
				
		   }   		
	
    </script>

<?
			 for($i=1; $i<=3; $i++)
			 {
			   
			   switch($i)
			   {
			      case 1 : $que = "1st"; break;
			      case 2 : $que = "2rd"; break;
			      case 3 : $que = "3nd"; break;				  
			   
			   }
			   
			  
			?>
			<div style="height:15px;"></div>
			
			<span style="color:#FF9200;">Please give us some information about your <?=$que?> photo :</span>
			<div style="height:15px;"></div>
			
            <table width="479" border="0" cellspacing="3" cellpadding="2">
              <tr>
                <td width="135" align="right" valign="top">Your <?=$que?> Photo* :</td>
                <td width="5">&nbsp;</td>
                <td width="335" align="left" valign="top"><input name="picture[]" type="file" id="picture[]" /></td>
              </tr>
              <tr>
                <td align="right" valign="top">Photo Name* :</td>
                <td>&nbsp;</td>
                <td align="left" valign="top"><input name="photo_name[]" type="text" id="photo_name[]" style="width:230px;" /> </td>
              </tr>
              <tr>
                <td align="right" valign="top">Photo Description* :</td>
                <td>&nbsp;</td>
                <td align="left" valign="top"> <textarea name="photo_desc[]" id="photo_desc[]" style="width:230px; height: 100px;"></textarea></td>
              </tr>
            </table>
            			
			<div style="width:525px; border-bottom:solid 1px #212121; padding: 5px;"></div>
			<?
			}
			?>
						
          </div>
          <div class="meta">
          
          </div>
        </div>
		
		

<div align="right" style="width:560px;"><input class="button" type="submit" value="Next Step >>" onclick="return check_data()"/></div>
</form>