vedi se questo può esserti utile:

<script>
function sendform()
{
if(document.form_name.text_name.value != "")
document.form_name.submit()
else
alert('vuoto')
}
</script>

<form name="form_name" action="javascript: alert('ho sottomesso il form')">
<input name="text_name" type="text" value="" onBlur="javascript:sendform()" >
</form>

ciao

barbara