Develop Reference

window.location.reload(true); doesn't work together with database question

I have a countdown script that takes the countdown date from a database. When the countdown is finished the page should reload and then get a new date from the database and then start a new counter. All is working as it should, but after the reload it seems that it doesn't get the time to ask the new question from the database. So the counter just sits at zero on the expired date. I've tried so many different ways to reload the page and none are working.
<?php
include '../includes/db.php';
$sql = $conn->query("SELECT gamedate FROM games WHERE gamedate > NOW() ORDER BY gamedate LIMIT 0 , 1 ") or die($conn->error());
while ($row = mysqli_fetch_array($sql))
{
$gamedate = $row['gamedate'];
}
?>
<div class="game" data-date="<? echo $gamedate; ?>" id="Countdown"></div>
<script>
$(".game").TimeCircles({count_past_zero: false},).addListener(countdownComplete);
function countdownComplete(unit, value, total){
if(total <= 0){
window.location.reload(true);
}
}
</script>

db table not getting updated when forcing logout using ajax

As stated in the title, db table trace_users is not getting updated when no activity happens for 30 mins but its get updated when its 6 mins.
The following code (both JS and PHP) is inside the same php file mno.php.
I am storing the last activity of user through this line let lastActivity = <?php echo time(); ?> ; present in the script below.
<?php
session_start();
if (isset($_GET['action']) && $_GET['action'] == "logout")
{
session_destroy(); // destroy session data in storage
!isset($_SESSION['admin']);
$open = "false";
$write = "0";
$stmt = $connect->prepare("UPDATE trace_users SET open=?, write=? WHERE user_name=?");
$usname = !empty($_SESSION['user_name']) ? $_SESSION['user_name'] : '';
$stmt->bind_param('sss', $open, $write, $usname);
$stmt->execute();
}
?>
<script>
jQuery(document).ready(function($) {
let lastActivity = <?php echo time(); ?> ; // storing last activity of user
let now = <?php echo time(); ?> ;
let logoutAfter = 360;
let timer = setInterval(function() {
now++;
let delta = now - lastActivity;
console.log(delta);
if (delta > logoutAfter) {
clearInterval(timer);
//DO AJAX REQUEST TO close.php
$.ajax({
url: "/abc/mno.php",
type: 'GET',
data: {
action: 'logout'
}, // Line A
success: function(data) {
console.log(data); // Line B
},
error: function(jqXHR, textStatus, errorThrown) {
alert(textStatus);
}
});
}
}, 1000);
});
</script>
Problem Statement:
I am wondering what changes I should make in the code above so that when no activity happens for 30 mins (1800 seconds) then the db table should also get updated.
Case1 (Not Working) : 1800 seconds (page logs out, db doesn't update)
Case2 (Working) : 360 seconds (page logs out, db gets updated)
The values inside session.gc_maxlifetime are 1440(Local Value) 1440(Master Value)
This is what I have tried/debugged:
On the network tab, I am getting Request Method GET when session timeout is set 6 mins and 60 mins.

You need to pass to the javascript some sort of permanent UID that identifies the user even after the session expires.
For the sake of simplification, I'm using user_name that already exists in your code. But you can also assign an UUID for each user, so that one can't guess another user's name and can't modify their stats.
First, you'll pass the $_SESSION['user_name'] from PHP to the JS closure.
let userName = "<?php echo $_SESSION['user_name']; ?>"; // don't forget to wrap the JS string value in quotes or apostrophes
Then, you'll pass it in the AJAX request payload.
data: {
action: 'logout',
user_name: userName // added param
},
Finally, you'll overwrite the value that is sent to DB (if it's sent with the payload)
$usname = !empty($_SESSION['user_name']) ? $_SESSION['user_name'] : ''; // original line
if (isset($_GET['user_name']) && !empty($_GET['user_name'])) {
$usname = $_GET['user_name'];
}
$stmt->bind_param('sss', $open, $write, $usname); // original line
Complete updated code:
<?php
if (isset($_GET['action']) && $_GET['action'] == "logout")
{
session_destroy(); // destroy session data in storage
!isset($_SESSION['pageadmin']);
$open = "false";
$write = "0";
$stmt = $connect->prepare("UPDATE trace_users SET open=?, write=? WHERE user_name=?");
$usname = !empty($_SESSION['user_name']) ? $_SESSION['user_name'] : '';
if (isset($_GET['user_name']) && !empty($_GET['user_name'])) {
$usname = $_GET['user_name'];
}
$stmt->bind_param('sss', $open, $write, $usname);
$stmt->execute();
}
?>
<script>
jQuery(document).ready(function($) {
let lastActivity = <?php echo time(); ?> ; // storing last activity of user
let now = <?php echo time(); ?> ;
let logoutAfter = 10;
let userName = "<?php echo $_SESSION['user_name']; ?>";
let timer = setInterval(function() {
now++;
let delta = now - lastActivity;
console.log(delta);
if (delta > logoutAfter) {
clearInterval(timer);
//DO AJAX REQUEST TO close.php
$.ajax({
url: "/abc/mno.php",
type: 'GET',
data: {
action: 'logout',
user_name: userName
}, // Line A
success: function(data) {
console.log(data); // Line B
},
error: function(jqXHR, textStatus, errorThrown) {
alert(textStatus);
}
});
}
}, 1000);
});
</script>
Few notes at the end:
It's bad practice to combine PHP, HTML and JS altogether in one file.
There are some parts of your code that are not easily reproducible and I had to guess from the context (e.g. i guessed that the session is already set, jQuery is used but there's no <script src="...jquery.js">, there's a DB query but no separate SQL import to try it quickly). Please read and apply the knowledge from How to create a Minimal, Reproducible Example in your next question, so that more people are able or willing to help you with it.

The problem is that you are not changing anything that will prevent the session from expiring after N seconds, you are just coding your script in a way that it will destroy the session after this time. The session gc (garbage colector) executes periodically and deletes old sessions and when that happens, $_SESSION['LAST_ACTIVITY'] will be deleted as well.
You must either try to prevent the gc from deleting sessions or change the logic in your application.

PHP process does not sit indefinitely and does not have program structure as a loop ala Node.js server, which won’t allow you to react to session expiry since it’s not a process that invalidates it, but rather a simple timestamp associated with session that is checked every time you attempt to work with it.
The solution I offer is a simple script that is ran every N minutes to perform a comparison of last user activity timestamp (which, I assume is updated on the request for that user) against expiry period (in you case it is 30 minutes). You can also set session expiry to 30 minutes, though strictly it’s not necessary. If the time difference will exceed 30 minutes, you update the timestamp for the user in your table, and invalidate their session if necessary. The script can be ran through cron or its alternatives and go through all users you require to perform a check.
Do not forget to handle the case when user is logged out on the server but client does not know about it and may continue sending logout requests - raising alert box is rather unclear (it is better to return HTTP Unauthorized code and handle it differently - redirecting to login screen, for example)

There are two things you need to fix.
1). Set the ajax request to be async:false.
$.ajax({
url: "/abc/mno.php",
type: 'GET',
async: false, // <---- ADDED ASYNC FALSE
data: {
action: 'logout'
}, // Line A
success: function(data) {
console.log(data); // Line B
},
error: function(jqXHR, textStatus, errorThrown) {
alert(textStatus);
}
});
2). Destroy the session after performing the SQL Query.
<?php
session_start();
if (isset($_GET['action']) && $_GET['action'] == "logout")
{
!isset($_SESSION['pageadmin']);
$open = "false";
$write = "0";
$stmt = $connect->prepare("UPDATE trace_users SET open=?, write=? WHERE user_name=?");
$usname = !empty($_SESSION['user_name']) ? $_SESSION['user_name'] : '';
$stmt->bind_param('sss', $open, $write, $usname);
$stmt->execute();
session_destroy(); // destroy session data in storage <---- DESTORY AT THE END
}
?>

Show preloader once per visit

I have been trying to figure this out, I want to show preloader only once per visit. How can I do that?
Current code:
$(window).on('load', function() {
$('#status').fadeOut();
$('#preloader').delay(350).fadeOut('slow');
$('body').delay(350).css({'overflow':'visible'});
})

Could you try the sessionStorage
if ( ! sessionStorage.getItem( 'doNotShow' ) ) {
sessionStorage.setItem( 'doNotShow', true );
$('#preloader').delay(350).fadeOut('slow');
} else {
$('#preloader').hide();
}
Or take a look on this link How to show website preloader only once

No cookie whether session or persistent will provide a reliable solution to this problem. The only way I can see doing this properly would be to record the ip address of the visitor and check to see if that record matches one in a table:
If it doesn't, load the preloader.
If it does, don't load the preloader.
The only possible problem to this is people periodically clear the temp website data they collect so I would implement a timed record system and set it to a reasonable value like 30 days so if they haven't visited your site in 30 days we will presume they have cleared their cache and they will get the preloader, that would change the criteria to;
If visitor is new, load preloader
If visitor is old but less than 30 days, don't load preloader
If visitor is old and more than 30 days, delete record, create new record, load
preloader
Code example below;
#1: Detect IP
<?php
function myIp() {
$client = #$_SERVER['HTTP_CLIENT_IP'];
$forward = #$_SERVER['HTTP_X_FORWARDED_FOR'];
$remote = $_SERVER['REMOTE_ADDR'];
if(filter_var($client, FILTER_VALIDATE_IP))
{
$ip = $client;
}
elseif(filter_var($forward, FILTER_VALIDATE_IP))
{
$ip = $forward;
}
else
{
$ip = $remote;
}
return $ip;
}
$my_ip = myIp();
global $my_ip;
?>
#2: Operations
<?php
// Set preloader status
$play_preloader = "no";
// Check visitor ip records for current ip
$preloader_one = "select ip from preloader where ip='$my_ip'";
$connect_preloader_one = mysqli_query($con, $preloader_one);
$rows_preloader_one = mysqli_num_rows($connect_preloader_one);
// If no record exists, create a new one
if ($rows_preloader_one == 0) {
$preloader_insert = mysqli_prepare($con, "insert into preloader (ip) values (?)");
mysqli_stmt_bind_param($preloader_insert, "s", $my_ip);
mysqli_stmt_execute($preloader_insert);
$play_preloader = "yes";
// If records exist, find records older than 30 days
} else {
$preloader_two = "select ip,date from preloader where ip='$my_ip' and date < DATE_SUB(now(), INTERVAL 30 DAY)";
$connect_preloader_two = mysqli_query($con, $preloader_two);
// If records older than 30 days found
$rows_preloader_two = mysqli_num_rows($connect_preloader_two);
if ($rows_preloader_two > 0) {
// Delete old records
$preloader_delete = "delete from preloader where ip='$my_ip' and date < DATE_SUB(now(), INTERVAL 30 DAY)";
$preloader_delete_query = mysqli_query($con, $preloader_delete);
// Add new record
$preloader_insert = mysqli_prepare($con, "insert into preloader (ip) values (?)");
mysqli_stmt_bind_param($preloader_insert, "s", $my_ip);
mysqli_stmt_execute($preloader_insert);
$play_preloader = "yes";
// If records exist but no records are older than 1 month
} else {
$play_preloader = "no";
}
}
// Preloader
if ($play_preloader == "yes") {
$preloader = "
enter you html/js/css code for the preloader here
";
} else {
$preloader = "";
}
?>
Now save all the above code in a php file then reference it in your html and then call $preloader;
<html>
<head>
<?php include_once ('mypreloader.php'); ?>
</head>
<body>
<?php echo $preloader; ?>
</body>
</html>
This code has been tested on a running server and is working.

Server Side Events & Historical Data

I am using PHP and MySQL in order to display live data on my webpage, refreshing every 1 second. All is currently working as expected although I would like to implement one new feature.
Currently on $( document ).ready() I start the live data feed by retrieving and displaying single rows of data from a transactions table. I can also start/stop the feed. Good so far.
I would now like to display the live data and have it start from the last 100 transactions. So for example, when a user opens the webpage they will initially see the past 100 transactions, then the live feed will start immediately afterwards (101, 102, 103, etc..).
Currently when the page is loaded the live feed starts at whatever transaction is returned by the sql query. Whereas I need it to start at that point minus 100
The past 100 transactions could -100 from the SerialNo as this is a unique, auto increment key in the database.
Everything is working regarding the live feed, including start/stop buttons. So I feel the issue is due to my query, especially the LIMIT 1 part. I have tried changing this to LIMIT 100 but when I do the webpage shows 100 records every 1 second.
I have two files, data.php and index.html. I have included the code for both below.
data.php
session_start();
include 'conn.php'; // database connection
header("Content-Type: text/event-stream");
header("Cache-Control: no-cache");
header("Access-Control-Allow-Origin: *");
$query = "SELECT TimeStamp, SerialNo FROM transactions ORDER BY TimeStamp DESC LIMIT 1";
$stmt = $conn->prepare($query);
$stmt->execute();
$result = $stmt->get_result();
while($row = $result->fetch_assoc()) {
//send request every x seconds
echo "retry: 1000\n\n";
echo "id: " .$row["SerialNo"]. "\n\n";
if ($_SESSION["lastSerialNo"] != $row["SerialNo"]) {
//store new "last" serial no in the session
$_SESSION["lastSerialNo"] = $row["SerialNo"];
//...send data to client
echo "data: ".$row['SerialNo']. ' ' .$row['TimeStamp']. "\n\n";
flush();
}
else {
// do nothing
}
}
index.html
<script type="text/javascript">
$("document").ready(function() {
// set the default stopped flag to false
var is_stopped = false;
var source = new EventSource("data.php");
var offline;
source.onmessage = function(event) {
if (is_stopped) {
// get data sent from data.php
offline = event.data;
// Put into storage
localStorage.setItem(event.lastEventId, offline);
// Retrieve from storage
offline = localStorage.getItem("offline");
}
if (!is_stopped) {
document.getElementById("result").innerHTML += "New transaction: " + event.data + "<br>";
}
};
$("document").ready(function() {
$("#start").click(function() {
// set stopped flag to false
is_stopped = false;
// loop through the localstorage
for (var i = 0; i < localStorage.length; i++) {
document.getElementById("result").innerHTML += "New transaction: " + localStorage.getItem(localStorage.key(i)) + " *<br>";
}
// clear local storage
localStorage.clear();
});
$("#stop").click(function() {
// set the stopped flag to true
is_stopped = true;
});
});
}); //end dom ready
</script>
<div id="result"><!--Server response here--></div>
<button id="stop"> stop</button>
<button id="start"> start</button>
Any help is appreciated.

Limit session user PHP

How can I forbid a user from logging in with the same account in two different browsers at the same time.
session_start();
// set time-out period (in seconds)
$inactive = 30;
if( is_user_logged_in() ) {
if (isset($_SESSION["timeout"])) {
// calculate the session's "time to live"
$sessionTTL = time() - $_SESSION["timeout"];
if ($sessionTTL > $inactive) {
session_destroy();
$redirect_to = isset($_REQUEST['redirect_to']) ? $_REQUEST['redirect_to'] : '/wordpress';
$location = str_replace('&', '&', wp_logout_url($redirect_to));;
header("Location: $location");
}
else{
wp_die('<h1>User is login! </h1>', '', array( 'back_link' => true ));
}
}
}

For this you need to Create a one more table for login logs , in that these will be fields
userID islogin (default=0) logintime useragent
if user is login each time update that login time.
and if user is try to login then we need to check in that if user islogin =1 and logintime < session time . then die;
You need do that in wordpress i thing
so you need to add code filter for login function.
and on on init update the logintime
Thanks