Nice to have a full-blown client-side equivalent of schema definitions and validation rules, but for most of my forms, I just add it quickly and dirty. Sometime

Nice to have a full-blown client-side equivalent of schema definitions and validation rules, but for most of my forms, I just add it quickly and dirty. Sometimes it feels bad, but most web toolkits treat JavaScript as a second-class citizen and not an integrated part of its core (and no, throwing in a jQuery does not count). Yii framework (PHP) supports validation through Ajax (serializes the form, sends for regular server-side validation and displays the errors on the form). A godsend if your form does not change, and impossible to work with if it is dynamic (consider batch entries with "Add line" features, etc.). I haven't seen a seamless integration on this higher level.