After upgrading PHP from 5.2 to 5.6, the js submission success prompt box will no longer pop up!

Question

After upgrading php from 5.2 to 5.6, when submitting the message board form and pressing the submit button, the js submission success prompt box will not pop up. Can anyone tell me if the syntax of different versions of php needs to be adjusted? ,Thanks!

$fsql -> query ("select field_caption,field_name,field_null,value_repeat from {P}_feedback where groupid='$groupid' and use_field = '1' order by xuhao");                
$fieldArray = array();                
while ($fsql -> next_record ()) {                        
$field_caption = $fsql -> f ('field_caption');                        
$field_name = $fsql -> f ('field_name');                        
$field_null = $fsql -> f ('field_null');                        
$value_repeat = $fsql -> f ('value_repeat');                        
$nowvalue=$_POST[$field_name];                                                
if ($field_null == "1" && (!isset ($nowvalue) || $nowvalue == "")) {                                
echo $FormSendNTC1.$field_caption;                                
exit;                        
}                        
if ($value_repeat == "0" && $nowvalue != "") {                                
$tsql -> query ("select id from {P}_feedback_info where " . $field_name . "='" . $nowvalue . "' and groupid = '" .$groupid . "'");                                
if ($tsql -> next_record ()) {                                        
echo $field_caption.$FormSendNTC2;                                        
exit;                                
}                        
}                        
//读取字段的名称：                        
$fieldArray[$field_name] = $field_caption;                
}                                
$sql = "select groupname from {P}_feedback_group where id = $groupid";                
$fsql -> query($sql);                
$fsql -> next_record ();