codice:
<script language="JavaScript" type="text/javascript">
function conta(val) {
max=50
if (form.elements[val].value.length > max) {
form.elements[val].value = form.elements[val].value.substring(0,max)
rest = 0
}
else {
rest = max - form.elements[val].value.length
}
form.num.value = rest
}
</script>
codice:
<input type="text" name="campo" size="50" onKeyUp="conta(this.name)">
<input type="text" name="campodue" size="50" onKeyUp="conta(this.name)">
<input value="29" size="3" name="num" disabled>