2. What is Ajax ?
• an acronym for Asynchronous JavaScript and XML is a group of
interrelated web development techniques used on the client-side to
create asynchronous web applications. With Ajax, web applications can
send data to, and retrieve data from, a server asynchronously (in the
background) without interfering with the display and behavior of the
existing page. Data is usually retrieved using the XMLHttpRequest object.
Despite the name, the use of XML is not needed (JSON is often used
instead), and the requests do not need to be asynchronous.
• Ajax is not a single technology, but a group of
technologies. HTML and CSS can be used in combination to mark up and
style information. The DOM is accessed with JavaScript to dynamically
display, and to allow the user to interact with the information presented.
JavaScript and the XMLHttpRequest object provide a method for
exchanging data asynchronously between browser and server to avoid full
page reloads.
3. Technologies
• HTML (or XHTML) and CSS for presentation
• The Document Object Model (DOM) for
dynamic display of and interaction with data
• XML for the interchange of data.
• The XMLHttpRequest object for asynchronous
communication
• JavaScript to bring these technologies
together
8. Ajax
• create The XMLHttpRequest Object
variable=new XMLHttpRequest();
• Send a Request To a Server
- get request
xmlhttp.open("GET","demo_get2.asp?fname=ahmed&lname=farag",tr
ue);
xmlhttp.send();
- post request
xmlhttp.open("POST","demo_post.asp",true);
xmlhttp.send("fname=ahmed&lname=farag");
مكونات الاجاكس1- XML HTTP REQUEST وهي المسئولة عن الاتصال بالسيرفر JAVA SCRIPT -2 وهي المسئولة عن عرض العناصر بالصفحات وتتفاعل مع المستخدم XML -3 وهي عبارة عن وسيط بين السيرفر وصفحات HTMLCSS -4وهي تقوم بتسيق الصفحات
open(method,url,async) Specifies the type of request, the URL, and if the request should be handled asynchronously or not.method: the type of request: GET or POSTurl: the location of the file on the serverasync: true (asynchronous) or false (synchronous)send(string)Sends the request off to the server.string: Only used for POST requestsA cached file is not an option (update a file or database on the server)Sending a large amount of data to the server (POST has no size limitations)Sending user input (which can contain unknown characters), POST is more robust and secure than GET