JavaScript-
<script type="text/javascript">
function movetoNext(current, nextFieldID) {
if (current.value.length >= current.maxLength) {
document.getElementById(nextFieldID).focus();
}
}
</script>html-
<input type="text"
id="txtFirst"
size="4"
onkeyup="movetoNext(this,
'txtSecond')" maxlength="10" />
<input type="text"
id="txtSecond"
size="4"
onkeyup="movetoNext(this,
'txtThird')" maxlength="10" />
<input type="text"
id="txtThird"
size="5"
maxlength="11"
/>