Javascript fejl

Hejsa, jeg har fået kopiret en chat som fungere på JQUERY JAVASCRIPT OG PHP men der mangler dog en submit knap. Nogle der ved hvordan jeg får tilføjet den???
Her er code:
// default name is 'Guest'
if (!name || name === '$username') {
name = "$username";
}

// strip tags
name = name.replace(/(<([^>]+)>/ig,"");

// display name on page
$("#name-area").html("You are: <span>" + name + "</span>");

// kick off chat
var chat = new Chat();
$(function() {

chat.getState();

// watch textarea for key presses
$("#sendie").keydown(function(event) {

var key = event.which;

//all keys including return.
if (key >= 33) {

var maxLength = $(this).attr("maxlength");
var length = this.value.length;

// don't allow new content if length is maxed out
if (length >= maxLength) {
event.preventDefault();
}
}
});
// watch textarea for release of key press
$('#sendie').keyup(function(e) {

if (e.keyCode == 13) {

var text = $(this).val();
var maxLength = $(this).attr("maxlength");
var length = text.length;

// send
if (length <= maxLength + 1) {

chat.send(text, name);
$(this).val("");

} else {

$(this).val(text.substring(0, maxLength));

}


}
});

});
</script>


<textarea id="sendie" style="margin-top: -15px;" maxlength = '100' ></textarea>


Procces.php
<?php
error_reporting (E_ALL ^ E_NOTICE);
session_start();
$username = $_SESSION['username'];
$userid = $_SESSION['id'];


$function = $_POST['function'];

$log = array();

switch($function) {

case('getState'):
if(file_exists('chat.txt')){
$lines = file('chat.txt');
}
$log['state'] = count($lines);
break;

case('update'):
$state = $_POST['state'];
if(file_exists('chat.txt')){
$lines = file('chat.txt');
}
$count = count($lines);
if($state == $count){
$log['state'] = $state;
$log['text'] = false;

}
else{
$text= array();
$log['state'] = $state + count($lines) - $state;
foreach ($lines as $line_num => $line)
{
if($line_num >= $state){
$text[] = $line = str_replace("\n", "", $line);
}

}
$log['text'] = $text;
}

break;

case('send'):
$nickname = htmlentities(strip_tags($_POST['nickname']));
$reg_exUrl = "/(http|https|ftp|ftps)\:\/\/[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(\/\S*)?/";
$message = htmlentities(strip_tags($_POST['message']));
if(($message) != "\n"){

if(preg_match($reg_exUrl, $message, $url)) {
$message = preg_replace($reg_exUrl, '<a href="'.$url[0].'" target="_blank">'.$url[0].'</a>', $message);
}


fwrite(fopen('chat.txt', 'a'), "<span>". $username . "</span>" . $message = str_replace("\n", " ", $message) . "\n");
}
break;

}

echo json_encode($log);

?>

chat.js
/*
Created by: Kenrick Beckett

Name: Chat Engine
*/

var instanse = false;
var state;
var mes;
var file;

function Chat () {
this.update = updateChat;
this.send = sendChat;
this.getState = getStateOfChat;
}


//gets the state of the chat
function getStateOfChat(){
if(!instanse){
instanse = true;
$.ajax({
type: "POST",
url: "process.php",
data: {
'function': 'getState',
'file': file
},
dataType: "json",

success: function(data){
state = data.state;
instanse = false;
},
});
}
}

//Updates the chat
function updateChat(){
if(!instanse){
instanse = true;
$.ajax({
type: "POST",
url: "process.php",
data: {
'function': 'update',
'state': state,
'file': file
},
dataType: "json",
success: function(data){
if(data.text){
for (var i = 0; i < data.text.length; i++) {
$('#chat-area').append($("<p>"+ data.text +"</p>"));
}
}
document.getElementById('chat-area').scrollTop = document.getElementById('chat-area').scrollHeight;
instanse = false;
state = data.state;
},
});
}
else {
setTimeout(updateChat, 1500);
}
}

//send the message
function sendChat(message, nickname)
{
updateChat();
$.ajax({
type: "POST",
url: "process.php",
data: {
'function': 'send',
'message': message,
'file': file
},
dataType: "json",
success: function(data){
updateChat();
},
});
}