Question

When I do not use if condition($last_msg_id_db>$last_msg_id) in load.php file then jquery function works allright and keep checking the data after each half second.

However If i use, if condition , jquery function works only first time but after first time running, it did not work and stops working.

I think ,I am not placing the if condition in load.php at right place.Plz help Or suggest any alternative approach.

php file(Load.php) is here

 $last_msg_id=$_POST['last_msg_id'];

$sql=mysqli_query($db3->connection,"SELECT * FROM chat_com ORDER by id ASC");

$sql_m=mysqli_query($db3->connection,"SELECT max(id) as maxid  FROM chat_com");
$row_m=mysqli_fetch_array($sql_m);
$last_msg_id_db=$row_m['maxid'];
if($last_msg_id_db>$last_msg_id){

    while($row=mysqli_fetch_array($sql)){

        $textt=$row['mesg'];
        $textt2="$textt<br>";

        $response=array();

        $response['msg']=$textt2;
        $response['last_msg_id_db']=$last_msg_id_db;
        $final_response[]=$response;
    }
}
echo json_encode($final_response);

Jquery function is here.

var last_msg_id = 1;
function chat_com_one(id, name) {
  $('#chatcom').show('fast');
  (function chatcom_load_one(id, name) {
    alert(last_msg_id);
    $.post('load.php', {option:'chatcom_load_one', last_msg_id:last_msg_id},     function(data) {
        var json = eval('(' + data + ')');
        $.each(json, function(i, row) {
            $("#chatcom #commid #commidwin").append(row['msg']);
            last_msg_id = row['last_msg_id_db'];
        });
        setTimeout(chatcom_load_one(id, name), 500);
    });
}(id, name));
$('#chatcom_send').click(function() {
    $.post('send.php', { option:'chat_com_send_one', text:$('#chatcom_text').val(), tocom:id}, function(data) {
        document.getElementById('chatcom_text').value = '';
    });
});
}

Answer 1

It may have not worked because $final_response may not have any data after second time ajax request and the condition could have failed to set values to $final_response.

You may have to initialize $final_response in top of the if condition,

$final_response = array();
if($last_msg_id_db>$last_msg_id){
   ...
   ...
}
echo json_encode($final_response);