using input type of 'image' instead of 'button' to fire js popup gives a different outcome

I have a page with a list of members created using databaridge and I have a button on each table row which loads a popup window of a members mini biography.
when the button is clicked, a hidden field in the form is updated with the member id and this is used as the get parameter in my popup form.

the button code is as follows...

<input type="button" class="formButton ResultsPageButton unstyled DetailButton" value="" onclick="document.getElementById('WADARecordID').value=<?php echo($row_WADAtblmember['MemberID']); ?>;document.getElementById('WADAMemberName').value='<?php echo($row_WADAtblmember['MemberFirstName']." ".$row_WADAtblmember['MemberLastName'] ); ?>';openWindow();" />

I would like to change the code so that the form uses an image input type instead, so I created the following, which calls the same javascript function

<input type="image" src="../../../images/buttons/view_button_grey.png" value="preview" title="View Details" onclick="document.getElementById('WADARecordID').value=<?php echo($row_WADAtblmember['MemberID']); ?>;document.getElementById('WADAMemberName').value='<?php echo($row_WADAtblmember['MemberFirstName']." ".$row_WADAtblmember['MemberLastName'] ); ?>';openWindow();" />

but when I tried this, the popup form opens and closes again, whereas it should stay open modally, (the same function is called)

here is my js function...

function openWindow() {	
   $.window({
   title: "Member Profile - "+document.getElementById('WADAMemberName').value,
   url: "/members/member_profile.php?MemberID="+document.getElementById('WADARecordID').value,
   width: 320,           // window width
   height: 600,          // window height
   draggable: false,
   resizable: false,
   maximizable: false,
   minimizable: false,
   showModal: true
});   
	}

see private message

ok

I must be missing something?

On that page the update image is a link?

<a href="/admin/members/member_update.php?MemberID=2" title="Update Member"><img border="0" name="Update2" id="Update2" alt="Update" src="/images/buttons/edit_button_grey.png" /></a>

ok

I found a 'solution' to the problem, my table was held within a form, but as the form had nothing which required to be submitted, (the buttons were either links or called some js), I removed the form tags around the table and hey, it works.

So it seems my image button to call the js function performs ok unless it is held within a form.

Not sure why at this point, maybe the image button acts like a submit when in a form ?

However, the real answer is staring me in the face.

Don't change the button type at all, leave everything as created by databridge dataasist wizard, and simply change the button's appearance usingcss

  maybe the image button acts like a submit when in a form ?  

yes, this is exactly correct.

you can use either the image element or Submit element types to submit a form, since you had the image elements in form tags, it was triggering the form submit.

thanks Jason, that clears it up, and i can do what I need with CSS, so all is well

;-)