Start learning with our library of video tutorials taught by experts. Get started

JavaScript and AJAX
Watching:

What is AJAX?


From:

JavaScript and AJAX

with Ray Villalobos

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.

Watch this entire course now—plus get access to every course in the library. Each course includes high-quality videos taught by expert instructors.

Become a member
Please wait...
JavaScript and AJAX
1h 12m Intermediate Jan 18, 2013

Viewers: in countries Watching now:

The ability to read data and communicate information asynchronously is fundamental to modern web applications. In this course, author Ray Villalobos takes a look at integrating AJAX (Asynchronous JavaScript and XML) with JavaScript and jQuery—a combination that makes it easy to work with dynamic data and reduces the number of requests to the server. The course first explains what AJAX is, and shows how to load and reload pages with pure JavaScript, update the DOM, and read and parse data in the XML and JSON formats. Next, learn how to read and write information between the server and the client with AJAX methods in jQuery, and build a dynamic search application that updates search results as you type.

Topics include:
  • What is AJAX?
  • Making requests asynchronous
  • Updating the DOM with getElementById
  • Reading JSON files
  • Working with jQuery and AJAX
  • Sending and searching JSON data
  • Incorporating CSS transitions
Subjects:
Developer Web Programming Languages Web Development
Software:
Ajax JavaScript
Author:
Ray Villalobos

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.

There are currently no FAQs about JavaScript and AJAX.

Share a link to this course
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.
Upgrade now


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.

Upgrade now

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
Welcome to the redesigned course page.

We’ve moved some things around, and now you can



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.

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