<script language="javascript">...function submitonce(theform)...{if (document.all||document.getElementById)...{for (i=0;i<theform.length;i++)...{var tempobj=theform.elements[i]if(tempobj.type.toLowerCase() =="image"||tempobj.type.toLowerCase()=="reset")tempobj.disabled=truealert("dd");}}}</script><form id="form1" name="form1" method="post" action="" onsubmit="javascript:submitonce(this);"> <label></label> <label> <input type="text" name="textfield" /> </label> <input type="image" name="imageField" src="btn.jpg" /></form>