chat session in chatbox in php

1//Updates the chat
2function updateChat(){
3  $.ajax({
4
5    type: "GET",
6    url: "update.php",
7    data: {  
8        'state': state,
9        'file' : file
10        },
11    dataType: "json",
12    cache: false,
13    success: function(data) {
14
15        if (data.text != null) {
16            for (var i = 0; i < data.text.length; i++) {  
17            $('#chat-area').append($("<p>"+ data.text[i] +"</p>"));
18        }
19
20        document.getElementById('chat-area').scrollTop = document.getElementById('chat-area').scrollHeight;
21
22    }  
23
24    instanse = false;
25    state = data.state;
26    setTimeout('updateChat()', 1);
27
28    },
29  });
30}
31

1var lastTimeID = 0;
2
3$(document).ready(function() {
4  $('#btnSend').click( function() {
5    sendChatText();
6    $('#chatInput').val("");
7  });
8  startChat();
9});
10
11function startChat(){
12  setInterval( function() { getChatText(); }, 2000);
13}
14
15function getChatText() {
16  $.ajax({
17    type: "GET",
18    url: "/refresh.php?lastTimeID=" + lastTimeID
19  }).done( function( data )
20  {
21    var jsonData = JSON.parse(data);
22    var jsonLength = jsonData.results.length;
23    var html = "";
24    for (var i = 0; i < jsonLength; i++) {
25      var result = jsonData.results[i];
26      html += '<div style="color:#' + result.color + '">(' + result.chattime + ') <b>' + result.usrname +'</b>: ' + result.chattext + '</div>';
27      lastTimeID = result.id;
28    }
29    $('#view_ajax').append(html);
30  });
31}
32
33function sendChatText(){
34  var chatInput = $('#chatInput').val();
35  if(chatInput != ""){
36    $.ajax({
37      type: "GET",
38      url: "/submit.php?chattext=" + encodeURIComponent( chatInput )
39    });
40  }
41}
42