auto reload page in chat php

1$(document).ready(function() {
2  // check once in five seconds
3  setInterval(function() {
4    $.get('/script.php', {do: 'new_messages'}, function(response) {
5      if(response == 1) {
6        window.location.reload();
7      }
8    });
9  }, 5000); 
10});
11

1$sql = "select * from chat order by id desc limit 15";
2    $result = mysql_query($sql) or die ("An error has occured with in the database.");
3
4