Take AJAX to your Email Inbox: Developing the Client-side Application Layer - Integrating the POP 3 client: listing the complete source code of the application
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As I said before, below is the complete client-side code for building the POP3 client, including the CSS, in conjunction with the (X)HTML markup:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>AJAX-BASED POP3 CLIENT</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-
8859-1" />
<script language="javascript">
var index=0;
function sendHttpRequest(url,callbackFunc,respXml){
var xmlobj=null;
try{
xmlobj=new XMLHttpRequest();
}
catch(e){
try{
xmlobj=new ActiveXObject("Microsoft.XMLHTTP");
}
catch(e){
alert('AJAX isn't supported by your browser!');
return false;
}
}
xmlobj.onreadystatechange=function(){
if(xmlobj.readyState==4){
if(xmlobj.status==200){
respXml?eval
(callbackFunc+'(xmlobj.responseXML)'):eval
(callbackFunc+'(xmlobj.responseText)');
}
}
}
// open socket connection
xmlobj.open('POST',url,true);
// send http header
xmlobj.setRequestHeader('Content-Type','application/x-www-
form-urlencoded; charset=UTF-8');
// get form values and send http request
xmlobj.send(getFormValues(document.getElementsByTagName
('form')[0]));
}
// get form values
function getFormValues(fobj){
var str='';
for(var i=0;i< fobj.elements.length;i++){
str+=fobj.elements[i].name+'='+ escape(fobj.elements
[i].value)+'&';
}
str=str.substr(0,(str.length-1));
return str;
}
// fetch messages from POP3 server
function fetchMessages(messages){
// build messages array
var messages=messages.split('||||');
var mdiv=document.getElementById('mailcontainer');
if(!mdiv){return};
// display mail server response
mdiv.innerHTML=messages[0];
// get 'previous' button
var prev=document.getElementsByTagName('form')[1].elements
['prev'];
if(!prev){return};
// get 'next' button
var next=document.getElementsByTagName('form')[1].elements
['next'];
if(!next){return};
// get 'clear' button
var clear=document.getElementsByTagName('form')[1].elements
['clear'];
if(!clear){return};
// move messages pointer back
prev.onclick=function(){
index--;
if(index<0){index=0};
mdiv.innerHTML=messages[index];
}
// move messages pointer forward
next.onclick=function(){
index++;
if(index==messages.length){index=messages.length-1};
mdiv.innerHTML=messages[index];
}
// clear mail container
clear.onclick=function(){mdiv.innerHTML=''};
}
// initialize user panel
function initializeUserPanel(){
// get 'connect' button
var sendbtn=document.getElementsByTagName('form')[0].elements
['connect'];
// send http request when button is clicked on
sendbtn.onclick=function(){
// send request & fetch messages from POP3 server
sendHttpRequest('pop_processor.php','fetchMessages');
// display 'Retrieving...' message
var mdiv=document.getElementById('mailcontainer');
if(!mdiv){return};
mdiv.innerHTML='Retrieving messages from the server...';
}
}
// initialize user panel when page is loaded
window.onload=function(){
// check if browser is DOM compatible
if(document.createElement&&document.getElementById&&document.
getElementsByTagName){
// initialize user panel
initializeUserPanel();
}
}
</script>
<style type="text/css">
body {
margin: 10px 0 0 0;
}
#userinfo {
width: 700px;
height: 22px;
padding: 2px 5px 2px 5px;
border-top: 2px solid #000;
border-left: 2px solid #000;
border-right: 2px solid #000;
background: #9cf;
margin-left: auto;
margin-right: auto;
font: bold 11px Verdana, Arial, Helvetica, sans-
serif;
color: #000;
}
#mailcontainer {
width: 700px;
height: 520px;
padding: 2px 5px 2px 5px;
border: 2px solid #000;
background: #eee;
margin-left: auto;
margin-right: auto;
font: 12px normal Arial, Helvetica, sans-serif;
color: #000;
overflow: auto;
}
#navbar {
width: 700px;
height: 22px;
padding: 2px 5px 2px 5px;
border-left: 2px solid #000;
border-right: 2px solid #000;
border-bottom: 2px solid #000;
background: #9cf;
margin-left: auto;
margin-right: auto;
}
form {
display: inline;
}
.inputbox {
width: 150px;
border: 1px solid #000;
background: #eee;
}
.formbutton {
width: 70px;
height: 20px;
font: bold 11px Verdana, Arial, Helvetica, sans-
serif;
color: #000;
}
</style>
</head>
<body>
<div id="userinfo">
<form>
HOST <input name="host" type="text" class="inputbox" title="Enter
mail hostname" />
USER <input name="user" type="text" class="inputbox" title="Enter
username" />
PASSWORD <input name="pass" type="password" class="inputbox"
title="Enter password" />
<input name="connect" type="button" value="Connect"
class="formbutton" />
</form>
</div>
<div id="mailcontainer">
</div>
<div id="navbar">
<form>
<input name="prev" type="button" value="<< Prev" class="formbutton" title="Previous message" />
<input name="next" type="button" value="Next >>" class="formbutton" title="Next message" />
<input name="clear" type="button" value="Clear" class="formbutton" title="Clear all messages" />
</form>
</div>
</body>
</html>
Bottom line
We're finished with this part now. Throughout this second part of the series I've gone through the definition of all the JavaScript functions, which are the building blocks of the POP3 client program on the client side. However, we need to cross the line and land on the server side, in order to create the PHP file that talks to the POP3 mail server. Want to see how this will be done? You'll have to wait for the last part!
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