recarregue a página usando ajax para criar um chat ao vivo

<script>
window.setInterval(function(){
{
var xmlhttp;
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","response.php",true);
xmlhttp.send();
}, 5000);
</script>
<div id="myDiv"><h2>This should be your chat box</h2></div>

<?php
//do the while loop for the amount of chat you want to see
//example

for ($i = 1; $i <= 10; $i++) {
    echo $i.'<br/>'; // Print out $i
}

?>