lobby.html

<script
  src="https://code.jquery.com/jquery-3.3.1.js"
  integrity="sha256-2Kok7MbOyxpgUVvAk/HJ2jigOSYS2auK4Pfzbm7uH60="
  crossorigin="anonymous"></script>
  
<script>
function checks() {
    getPlayers();
}


function getPlayers() {
$.get( `api/get_players.php?ID=<?php echo $_GET["ID"]; ?>`, function( data ) {
  players = data.split(":");
  $('#players').html(players.join("<br />"));
  //alert(data);
});
}
</script>
  
  
<center>
<h1>Welcome to the lobby for room <?php echo($_GET["ID"]); ?></h1>
<h3>Players currently in this lobby:</h3>
<div id='players'>Loading...</div>
</center>

<script>
setInterval(function() {
  checks();
}, 1000);

window.onload = function() {
  checks();
};
</script>