html type date onInvalid code example
Example: formatage date css
$date_array = explode("/",$date); // split the array
$var_day = $date_array[0]; //day seqment
$var_month = $date_array[1]; //month segment
$var_year = $date_array[2]; //year segment
$new_date_format = "$var_year-$var_day-$var_month"; // join them together