cake php client side validation example simple

<script type="text/javascript">
function validate_notempty(field,

alerttext) {

        if(field.value==null || field.value=="") {

                alert(alerttext);
                return false;
        }else {
                return true;
        }
}
function validate(thisform)        {

        if (validate_notempty(thisform.

user_name,"username cant be
empty")==false) {
                thisform.user_name.focus();

                return false;
        } else {
                return true;
        }
}
</script>

And the form:

<?php

echo $form->create(null, array('onsubmit'=>'return validate(this);'));
echo $form->input('user_name', array('div'=>false, 'size'=>25,
'label'=>'fd_back', 'class'=>'engInput'));
echo $form->end('submit_it', array('class'=>'engInput'));

?>