Event Handling Programming with AJAX

By: Courtney Ball and Brian Robbins

Traditional AJAX AJAX – Asynchronous JavaScript and

XML

Traditional AJAX Ajax is used to develop fast dynamic

web applications Allows web pages to be updated

asynchronously by transferring data server side behind the scenes

Ajax is not a programming language itself but uses various web development techniques such as JavaScript, PHP, HTML, CSS and XML

Traditional AJAX Ajax uses HTTP requests to serve as

the connection between the server and the user

Data is sent to the server, processed and immediately sent back to client side

Traditional Ajax

Event Driven AJAX Similar execution to traditional Ajax but

uses an XMLHttpRequest object Instead of using a continuous HTTP

connection, after a request is sent, the request is terminated, so there are new requests after each response

Event Driven AJAX

Our Project Using HTML, JavaScript and PHP, we

are creating a simple web page that displays 5 options of colors in which the user can change the background to their desired color

User Interface

Screen Shots

Coding Examples JavaScript for UI

//Function that is called by the forms in javascript function blue() { document.bgColor = "blue"; }

//Form for calling a specific color<input type="button" value="BLUE" onClick= "blue()" />

function blue() { var xhr; //try and catch block for particular web browser

try { xhr = new ActiveXObject('Msxml2.XMLHTTP');

} catch (e) { try { xhr = new ActiveXObject('Microsoft.XMLHTTP'); } catch (e2) { try { xhr = new XMLHttpRequest(); //Instantiates new XmlHttpRequest Object }

catch (e3) { xhr = false; } } }

xhr.onreadystatechange = function() {

if(xhr.readyState == 4) {

if(xhr.status == 200) document.bgColor = "blue"; else document.ajax.dyn="Error code " ; }

};

XMLHttpRequest object

Conclusion Ajax is effective for fast dynamic web

browsing, it is commonly used so that a user does not have to refresh the we browser to acquire new information

Conclusion Ajax is commonly seen in the popular

social network facebook

It is also used in eCommerce websites such as eBay

Most recent it is seen in Youtube