AJAX 2 Resume

Learn Ajax Quickly

2010-06-17T10:34:00.000-07:00

Nowadays Every Website Is Using Ajax and its worth that you know the basics of it during your interview.
Its Very Easy, So Just Learn the basics.
Follow These Links To Learn Ajax Quickly

1. Introduction To Ajax2Resume

2. What Is Ajax

3. XMLHttpRequest Object

4. Creation Of XMLHttpRequest Object

5. Properties Of XMLHttpRequest Object

6. Events In XMLHttpRequest Object

7. Methods In XMLHttpRequest Object

8.

Search Results

2010-06-08T02:05:00.001-07:00

6. Methods In XMLHttpRequest Object (Extended)

2010-06-07T23:47:00.005-07:00

The total methods in XMLHttpRequest Object are

Method	Description
abort	Cancels the current HTTP request.
getAllResponseHeaders	Returns the complete list of response headers.
getResponseHeader	Returns the specified response header.
open	Assigns method, destination URL, and other optional attributes of a pending request.
send	Sends an HTTP request to the server and receives a response.
setRequestHeader	Adds custom HTTP headers to the request.

These are the total methods and their descriptions. No need to memorize all. The
basic two methods are discussed here.

Go To Lesson 7

6. Methods In XMLHttpRequest Object

2010-06-07T23:47:00.003-07:00

In total there are 6 methods in the XMLHttpRequest Object, of which two are
important for the interview purpose. These are discussed below.

1. open() : Assigns method, destination URL, and other optional attributes of a
pending request.
This open method will open the communication channel between the client and
server to send the request
It takes 3 parameters as open(method, url, bool)

a) method: It indicates how the data is transmits between
the client and the server. It can be either get or post. In general get is used
as there is less data transmissions.
b) url: It specifies the address of the webpage where the request needs
to be processed.
c) bool: It can be either true or false. True indicates Asynchronous
Requests and False indicates Synchronous Requests.

2. send() : Sends an HTTP request to the server and receives a response.
It sends the request to the server by using the communication channel prepared
by the open method.
These are the important methods of XMLHttpRequest Object. To view all the methods click here.

Points To Remember:

The open method prepares the communication channel by specifying the method, url
and the type of request, then the send method sends the request using the
communication channel prepared by the open method.

Go to Lesson 7
or
View All The Methods

5. Events in XMLHttpRequest Object

2010-06-07T23:47:00.001-07:00

There are 2 events for this object and one of them is important. i.e.,
onreadystatechange. Remeber this name important for interviews.

onreadystatechange : This event sets or retrieves the event handler for asynchronous
requests.
This event is fired every time the value of the readyState property is changed.
Whenever there is a change we can recieve the response in the ReadyStateChange
event handler
The second event is ontimeout, Raised when there is an error that prevents the
completion of the request. Works from IE 8 onwards.

Points To Remember:

XMLHttpRequest Object has an event called "onreadystatechange" which is fired
everytime the readyState PROPERTY changes its value.

Go To Lesson 6

4. Properties of XMLHttpRequest Object (Extended)

2010-06-07T23:46:00.005-07:00

The total 8 properties in the XMLHttpRequest Object are described in the table
below. The Constructor and TimeOut propertes are the latest and works from IE 8
onwards.

Property	Description
constructor	Returns a reference to the constructor of an object.
readyState	Retrieves the current state of the request operation.
responseBody	Retrieves the response body as an array of unsigned bytes.
responseText	Retrieves the response body as a string.
responseXML	Retrieves the response body as an XML Document Object Model (DOM) object.
status	Retrieves the HTTP status code of the request.
statusText	Retrieves the friendly HTTP status of the request.
timeout	Gets or sets the time-out value.

No need to remeber all these. The main properties are already discussed in
detail here.

Go To Lesson 5

4. Properties of XMLHttpRequest Object

2010-06-07T23:46:00.003-07:00

Properties of XMLHttpRequest Object
Coming to the properties, there are totally 8 properties, here we are discussing
only 3 properties in detail which are almost enough and important. To see all the list of 8 properties click here.

1. readyState : This property will retrieve the current state of the request
operation

Syntax : [nState=] object.readyState

Here nState will be returned with the following values(0,1,2,3,4) only

0 (Uninitialized) The object has been created, but not initialized (the open
method has not been called).
1 (Open) The object has been created, but the send method has not been called.
2 (Sent) The send method has been called. responseText is not available. responseBody
is not available.

3 (Receiving) Some data has been received. responseText is not available.
responseBody is not available.

4 (Loaded) All the data has been received. responseText is available.
responseBody is available.

Based on the return value, the state of the request is known
2. responseText : Retrieves the response body as astring (from the server)
3. responseXML: Retrieves the response body as an XML Document Object Model
(DOM) object.

Example:
For page loading the status bar shows the loading of the page, but an ajax page
loading is not known so, we have to create our own labels to tell the user about
the process that is taking place.
For example, while registering in any website, if we give user name then the
request is gone to the server for the availability checking at that time we can
see PleaseWait or Checking Labels are displayed. This can be done using these
properties.
First we know the state by using the ready state and then appropriate message is
displayed using the 2,3 properties.

Points To Remember:

1. readyState : This property will retrieve the current state of the request
operation
2. responseText : Retrieves the response body as astring (from the server)
3. responseXML: Retrieves the response body as an XML Document Object Model
(DOM) object.

Go to Lesson 5
or
See The Extended properties Of XMLHttpRequest Object

3. Creation Of XMLHttpRequest Object

2010-06-07T23:46:00.001-07:00

In this lesson we learn how to create an XMLHttpRequest Object, generally as
AJAX is using JavaScript, the browser support is needed for an AJAX enabled
application to work correctly. All modern browsers (IE7+, Firefox, Chrome,
Safari, and Opera) has a built-in XMLHttpRequest object. So for these browsers
it is same as creation of the object in Java or .NET, etc i.e., using the NEW
operator.

xmlhttp=new XMLHttpRequest();

But For Older versions we have to use an ActiveXObject, which is not necessary
in the present days. Its syntax is

xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

That's it for the creation of the XMLHttpRequest Object

Points To Remember:

Browser support is required to run the AJAX enabled website & all the modern
browsers support it.
XMLHttpRequest Object is created using the NEW operator xmlhttp=new
XMLHttpRequest();

Go To Lesson 4

What is AJAX? (In Detail)

2010-06-07T12:19:00.001-07:00

2. XMLHttpRequest Object

2010-06-07T12:18:00.001-07:00

Don’t Fear by seeing the title, I gave the title because it is an important

thing that will be asked in interviews, so remember the name.

In AJAX
enabled applications data is exchanged with a server behind the scenes using the
XMLHttpRequest Object, so learning about this object is very
important.(especially for interviews)

Don’t bother about the coding and examples first learn the basics.

So let us learn

How to create XMLHttpRequest Object
Properties of XMLHttpRequest Object
Events of XMLHttpRequest Object
Methods of XMLHttpRequest Object

Points To Remember:

In AJAX enabled
applications data is exchanged with a server behind the scenes using the
XMLHttpRequest Object

Go To Lesson 3

What is AJAX?

2010-06-07T12:15:00.000-07:00

AJAX, Asynchronous Javascript And XML is not a new technology, but it is an important improvement over existing client side technologies.

With the help of AJAX we can develop more interactive web pages.

The best example of AJAX is the Suggestions Of the Google which appear dynamically as we type in the search box.

Also many webpages while on the registration they will check the availability of the username automatically, through AJAX.

From these examples, I hope you got something about AJAX.

It can connect to the server(or database) and retrieves information without the page reload.

That means When we want a part of a web page to be updated automatically we can use AJAX, instead of reloading the entire web page.

The name itself says that Javascript+XML =AJAX.

Don’t Fear, you may continue learn this even though you don’t know anything about Javascript & XML. (Very little bit of JavaScript appreciated).

Nowadays almost every website is using AJAX, to develop interactive websites, so that they can give fast accessing to the users and less burden on the server.

If you have more time and want to learn more about what is AJAX, click here

Otherwise move to Lesson2

Introduction To AJAX To Resume

2010-06-07T11:52:00.000-07:00

Hi, guys
The main motto of this blog is to make the techy guys especially students and working IT professionals to add AJAX in their Resumes.
Hope you all understand What i am saying.
Here is a very quick tutorial covering all the basics especially required to answer in an interview.
So Lets Start.

Move To First lesson What Is Ajax