DanKud

$str = 'полная_строка_из_БД';
if (strlen($str) > 30) $str = substr($str, 0, 30) . '...';
echo $str;

$arr = [];
$show = false;

while ($hero2 = mysqli_fetch_assoc($hero1)) {
    $time_now = strtotime($hero2['cron1']);
    $time_need = strtotime($hero2['cron2']);

    if ($time_need >= $time_now) {
        $t_s = date("H:i ", 75600 - ($time_need - $time_now));
    }
    else {
        $t_s = date("H:i ", 75600 - ($time_now - $time_need));
        if (!$show) $show = true;
        $arr[] = str_replace(":", ".", $t_s);
    }
}

if ($show) {
    echo '[' . implode(',', $arr) . ']';
}

if ($role = '1') {
    header('Location: user.php');
    ......