javascript - AJAX whenever I try to submit my text my div area duplicates the current data displayed plus my new data -

hi have working script of retrieving json data result small chat application problem displays duplicate result of text posted plus newly text inserted db

here whole javascript code:

    function sendchattext() {                  if (sendreq.readystate == 4 || sendreq.readystate == 0) {                     sendreq.open("post", 'includes/getchat.php?last=' + lastmessage, true);                     sendreq.setrequestheader('content-type','application/x-www-form-urlencoded');                     sendreq.onreadystatechange = ajaxretrieve();                       var param = 'message=' + document.getelementbyid('txta').value;                     param += '&name='+user;                     param += '&uid='+uid;                     param += '&rid='+document.getelementbyid('trg').value;                     sendreq.send(param);                     document.getelementbyid('txta').value = '';                 }                                        }  function ajaxretrieve()             {                   var rid = document.getelementbyid('trg').value,             data = {chat: uid, rid: rid, name: user};  $.ajax({       url: "includes/getchat.php",       type: "get",       data: data,       datatype: 'json',     success: function(result){      $.each(result, function(rowkey, row) {          $("#clog").append($('<p />').html('<h4>'+ row.username +':</h4>' + row.message_content) );         });     }  });   } 

i think getchat.php returns chat text user, appending them #clog.

i have 2 suggestions

1. return latest text server sending time stamp js like

   data = {"chat": uid, "rid": rid, "name": user, "last_read_time": window.last_read_time}; window.last_read_time = new date().format("d/m/yyyy hh:mm:ss tt"); //store new time 

2. clear #clog before looping data

   $("#clog").empty(); //clear previous msgs $.each(result, function(rowkey, row) {     $("#clog").append($('<p />').html('<h4>'+ row.username +':</h4>' + row.message_content); });