Easy-to-follow video tutorials help you learn software, creative, and business skills.Become a member

What is AJAX?

From: JavaScript and AJAX

Video: What is AJAX?

So you may be wondering what AJAX is and why you want to learn more about it, so let's take a look at how you can use AJAX with JavaScript to build dynamic web applications. Before we look at AJAX, let's talk about how a browser gets information to display a page. When a browser requests a page from a website, the browser in your machine is acting as a client. The website is being delivered through a machine that is serving up the information, so we call that a server. When you ask for a page, the client makes a request to the server and the server returns a page. Sometimes when you're looking at a page, you may want to ask for some additional information from the server.

What is AJAX?

So you may be wondering what AJAX is and why you want to learn more about it, so let's take a look at how you can use AJAX with JavaScript to build dynamic web applications. Before we look at AJAX, let's talk about how a browser gets information to display a page. When a browser requests a page from a website, the browser in your machine is acting as a client. The website is being delivered through a machine that is serving up the information, so we call that a server. When you ask for a page, the client makes a request to the server and the server returns a page. Sometimes when you're looking at a page, you may want to ask for some additional information from the server.

Say for example that your page has thumbnails for a photo album and perhaps the album has more thumbnails than you can see in the current view. Without AJAX if you want to see more thumbnails, you'd have to make a request back to the server and it would send you a whole new page with additional thumbnails. That means the server ends up sending a lot of information that you don't really need all over again. With AJAX, the server doesn't have to send you the whole page; it just sends the pieces you need-- in this case new thumbnails. So how does that work? AJAX is not a single technology, but a group of technologies working together to make that happen.

Technically, AJAX stands for Asynchronous JavaScript and XML. That's quite a mouthful, so let's break that down piece by piece. Asynchronous means that the client can request new pieces of information from the server at any time. It doesn't have to wait for a page to reload. A new request can be triggered by an event like clicking on a button, hovering over an image, or whatever. The J in AJAX stands for JavaScript. JavaScript is where all this magic takes place. It handles the events that trigger a new request, makes the requests for new data to the server, and takes care of updating only the part of the document that needs to change.

JavaScript talks to the server through a set of programming methods called an API and uses what's called an XHR or XML HTTP request. This is where the X in AJAX comes from. The XHR API lets the browser send and request data from a server. This can be a bit confusing because a lot of people think of XML as a language used to describe data that's a lot like HTML. Sometimes people assume that the X in AJAX means that the data from an AJAX request has to be in XML, but the data that gets transferred to and from the server can be in any format, and it's usually either a text file, HTML, or a JavaScript object, like JSON.

So AJAX is really just a fancy term for a technology that lets you build pages that update without requiring a page reload. JavaScript does most of the heavy lifting with AJAX, and it uses the XHR API to handle the communication between the client and the server.

Show transcript

This video is part of

Image for JavaScript and AJAX
JavaScript and AJAX

21 video lessons · 19466 viewers

Ray Villalobos
Author

 

Start learning today

Get unlimited access to all courses for just $25/month.

Become a member
Sometimes @lynda teaches me how to use a program and sometimes Lynda.com changes my life forever. @JosefShutter
@lynda lynda.com is an absolute life saver when it comes to learning todays software. Definitely recommend it! #higherlearning @Michael_Caraway
@lynda The best thing online! Your database of courses is great! To the mark and very helpful. Thanks! @ru22more
Got to create something yesterday I never thought I could do. #thanks @lynda @Ngventurella
I really do love @lynda as a learning platform. Never stop learning and developing, it’s probably our greatest gift as a species! @soundslikedavid
@lynda just subscribed to lynda.com all I can say its brilliant join now trust me @ButchSamurai
@lynda is an awesome resource. The membership is priceless if you take advantage of it. @diabetic_techie
One of the best decision I made this year. Buy a 1yr subscription to @lynda @cybercaptive
guys lynda.com (@lynda) is the best. So far I’ve learned Java, principles of OO programming, and now learning about MS project @lucasmitchell
Signed back up to @lynda dot com. I’ve missed it!! Proper geeking out right now! #timetolearn #geek @JayGodbold
Share a link to this course

What are exercise files?

Exercise files are the same files the author uses in the course. Save time by downloading the author's files instead of setting up your own files, and learn by following along with the instructor.

Can I take this course without the exercise files?

Yes! If you decide you would like the exercise files later, you can upgrade to a premium account any time.

Become a member Download sample files See plans and pricing

Please wait... please wait ...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Join now "Already a member? Log in

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed JavaScript and AJAX.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Are you sure you want to delete this note?

No

Your file was successfully uploaded.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked
Terms and conditions of use

We've updated our terms and conditions (now called terms of service).Go
Review and accept our updated terms of service.