AJAX is a developer's dream

AJAX Introduction

AJAX is a developer's dream, because you can:

Update a web page without reloading the page
Request data from a server - after the page has loaded
Receive data from a server - after the page has loaded
Send data to a server - in the background

What is AJAX?
AJAX = Asynchronous JavaScript And XML.

AJAX is not a programming language.

AJAX just uses a combination of:

A browser built-in XMLHttpRequest object (to request data from a web server)
JavaScript and HTML DOM (to display or use the data)
AJAX is a misleading name. AJAX applications might use XML to transport data,
but it is equally common to transport data as plain text or JSON text.

AJAX allows web pages to be updated asynchronously by exchanging data with
a web server behind the scenes. This means that it is possible to update parts of a web page,
without reloading the whole page.

1. An event occurs in a web page (the page is loaded, a button is clicked)
2. An XMLHttpRequest object is created by JavaScript
3. The XMLHttpRequest object sends a request to a web server
4. The server processes the request
5. The server sends a response back to the web page
6. The response is read by JavaScript
7. Proper action (like page update) is performed by JavaScript

jQuery AJAX Methods
AJAX is the art of exchanging data with a server, and update parts of a web page - without reloading the whole page.

The following table lists all the jQuery AJAX methods:

Method Description
$.ajax() Performs an async AJAX request
$.ajaxPrefilter() Handle custom Ajax options or modify existing options before each request is sent and before they are processed by $.ajax()
$.ajaxSetup() Sets the default values for future AJAX requests
$.ajaxTransport() Creates an object that handles the actual transmission of Ajax data
$.get() Loads data from a server using an AJAX HTTP GET request
$.getJSON() Loads JSON-encoded data from a server using a HTTP GET request
$.parseJSON() Deprecated in version 3.0, use JSON.parse() instead. Takes a well-formed JSON string and returns the resulting JavaScript value
$.getScript() Loads (and executes) a JavaScript from a server using an AJAX HTTP GET request
$.param() Creates a serialized representation of an array or object (can be used as URL query string for AJAX requests)
$.post() Loads data from a server using an AJAX HTTP POST request
ajaxComplete() Specifies a function to run when the AJAX request completes
ajaxError() Specifies a function to run when the AJAX request completes with an error
ajaxSend() Specifies a function to run before the AJAX request is sent
ajaxStart() Specifies a function to run when the first AJAX request begins
ajaxStop() Specifies a function to run when all AJAX requests have completed
ajaxSuccess() Specifies a function to run when an AJAX request completes successfully
load() Loads data from a server and puts the returned data into the selected element
serialize() Encodes a set of form elements as a string for submission
serializeArray() Encodes a set of form elements as an array of names and values