HELP in validating form

here is my form and the javascript that runs to check the form if the info. is enter or not

<script language="JavaScript" type="text/javascript">
		
		function checkform ( form )
		{

  		if (form.elements[0].value == "" || form.elements[0].value==NULL) 	

		{
    		alert( "Please enter your name." );
    		form.elements[0].focus();
    		return false;	
  		}
		
		if (form.elements[1].value == "" || form.elements[1].value==NULL) 	

		{		
    		alert( "Please enter your comment." );
    		form.elements[1].focus();
    		return false;
  		}
		
		return true;

		}
		
		</script>


<form name="myform" method='GET' action='addcomment.php' onsubmit="return 

checkform(this);">
            &nbsp;&nbsp;Your Name:<input type='text' name='name' id='name'  />
            <br />
            <table>
            <tr>
            <td valign="top">
			&nbsp;&nbsp;<p>Comment:</p> </td>
            <td >
            &nbsp;<textarea name='comment' rows='5' id='comment' ></textarea>
			</td>
            </tr>
            <tr>
            <td>
            <input type='submit' value='add' />
            </td>
            <td>
            <input type='reset'  />
            </td>
            </tr>
            
            <input type='hidden' value='<?php echo $temp?>' name='id'/>
            </table>
            </form>

Code (markup):

And the problem is I cant validate two field(name and comment)at the same time. I mean if I leave "comment" blank, the form would still be submitted. Another issue, if I change the order of the "if" statment above, the form would be submitted if I leave "name" blank.
another thing I want to mention that I tried to change the second "if" statment to "else if", but still doesnt work. Any help will be appreciated.

 

Here,
I went through your script and corrected a few minor things.
Try this:

<script language="JavaScript" type="text/javascript">
		
		function checkform (form)
		{


  		if (!form.elements[0].value) 	

		{
    		alert( "Please enter your name." );
    		form.elements[0].focus();
    		return false;	
  		}
		
		if (!form.elements[1].value) 	

		{
		
    		alert( "Please enter your comment." );
    		form.elements[1].focus();
    		return false;
  		}
		
		return true;
		}
		
		</script>


<form name="myform" method='GET' action='addcomment.php' onsubmit="return checkform(this);">
            &nbsp;&nbsp;Your Name:<input type='text' name='name' id='name'  />
            <br />
            <table>
            <tr>
            <td valign="top">
			&nbsp;&nbsp;<p>Comment:</p> </td>
            <td >
            &nbsp;<textarea name='comment' rows='5' id='comment' ></textarea>
			</td>
            </tr>
            <tr>
            <td>
            <input type='submit' value='add' />
            </td>
            <td>
            <input type='reset'  />
            </td>
            </tr>
            <input type='hidden' value='<?php echo $temp?>' name='id'/>
            </table>
            </form>

PHP: