<td align="left">验证码:<input name="checkcode" type="text" id="CheckCode" size="4" style="height:20px; width:40px;" class="editbox" maxlength="4"><div id="CodeDiv" style="cursor: pointer; top: 120px; width: 160px; height: 60px; position: absolute; z-index: 999; clip: rect(auto, auto, auto, auto); left: 726px;display:none;"><img src="code.asp" id = "CheckCodeImage" onclick="this.src='include/validatecode.asp?'+Math.random();" style="cursor:pointer"/></div> </td>

<script>
function idEm( eId ){return document.getElementById(eId);} 
idEm('CheckCode').onfocus = function(){
    idEm('CodeDiv').style.display = "";
    idEm('CheckCodeImage').src='code.asp?'+Math.random();
}
idEm('CodeDiv').style.top = idEm('CheckCode').style.top;
idEm('CodeDiv').style.left = idEm('CheckCode').style.left;
idEm('CheckCode').onblur = function(){idEm('CodeDiv').style.display = "none";}
</script>