html - How to dynamically modify a text file on a php site in real time

Question

I'm currently displaying a txt file on my website which is constantly being modified. Is there any way to display the modifications to the text file on the page in real time so I don't need to set a page refresh timer to see changes? The full code for my site can be found here. https://pastebin.com/JauZurS7

if (isset($_GET['enSubmit']) && isset($_GET['uname']) && isset($_GET['rname'])){
echo'<meta http-equiv="refresh" content="10">';
$room=$_GET['rname']; 
$uname=$_GET['uname'];
if (!is_dir($room)) mkdir($room);
$files = scandir($room);
foreach ($files as $user){
    if ($user=='.' || $user=='..') continue;
    $handle=fopen("$room/$user",'r');
    $time = fread($handle, filesize("$room/$user"));
    fclose($handle);
    if ((time()-$time)>1) unlink("$room/$user");
}
$contents='';
$filename="$room.txt";
if (file_exists($filename)){
    $handle = fopen($filename, "r");
    $contents = fread($handle, filesize($filename));
    fclose($handle);    
}
$handle = fopen("$room/$uname", "w");
fwrite($handle, time());
fclose($handle);

$files = scandir($room);
$users='';
foreach ($files as $user) if ($user!='.' && $user!='..') $users.=$user."
";

if (isset($_POST['Send'])){
    $text=$_POST['txt'];
    $contents.="$uname: $text";
    $handle = fopen("$filename", "a");
    fwrite($handle, "$uname: $text
");
    fclose($handle);
}

Currently, the chat system works by people sending text which is appended to a text file. The text file is updated but in order for users to see the changes from others they have to refresh the page. To combat this I set up a 10 second refresh timer, however the problem is that people who are typing at that time will have their work removed. I'm thinking of using filemtime to append the txt file but I'm not sure how to do that.

question from:https://stackoverflow.com/questions/65623030/how-to-dynamically-modify-a-text-file-on-a-php-site-in-real-time