New Feature: Playlist Center! Pick a topic and let our playlists guide the way.

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

JavaScript and AJAX
Illustration by
Watching:

Reading JSON files


From:

JavaScript and AJAX

with Ray Villalobos

Video: Reading JSON files

Although AJAX was designed to work with files in the XML format, it will read the contents of any text file. So the data can really be in any format; the trick is to know how to parse or translate the data into objects that JavaScript can manipulate. An obvious choice is to use the file in the JSON format. JASON stands for JavaScript Object Notation, and is a way to structure data so that it can be easily converted to a JavaScript object. If you want to learn more about JSON, make sure you check out my course on Building Facebook Applications with HTML and JavaScript. There is a section called Adding JSON Data Feeds, and it has a good introduction to the JSON language.

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

Reading JSON files

Although AJAX was designed to work with files in the XML format, it will read the contents of any text file. So the data can really be in any format; the trick is to know how to parse or translate the data into objects that JavaScript can manipulate. An obvious choice is to use the file in the JSON format. JASON stands for JavaScript Object Notation, and is a way to structure data so that it can be easily converted to a JavaScript object. If you want to learn more about JSON, make sure you check out my course on Building Facebook Applications with HTML and JavaScript. There is a section called Adding JSON Data Feeds, and it has a good introduction to the JSON language.

So, let's go back and take a look at what a JSON document looks like. If you watch the movie on parsing XML using AJAX, this is the same data, but in a slightly different format. The good news is that parsing data is super simple--sort of; some browsers support a parse command, so let's go into the JavaScript file and replace the code for processing or XML file. So, I'm going to modify this open command to open the JSON document. Now I'm going to take out the rest of this code right here, and I'll create a variable called items and set it to the JSON object and use the parse command with the responseText of the request. Then I'll output this to the console so we can look at it.

So let me save this and I'll switch back to a browser, refresh our page, And if you have the console openm remember that you could just right-click on this page and select Inspect Element if you are using Google Chrome like me. And I can see the series of objects that this returns. If I open that up, I can see each individual object and inside each object, I can see different name and value pairs. So this is a little different from what we would see with XML. It's essentially an array of objects and each object has a label and the data from our file.

So here's the bad news: JSON parse is not available in some older browsers. So, if you go to this website, you could see that it's available in most modern browsers, but a lot of the older versions of IE do not support the parse command. So your options are to use EVAL--but that has some security issues--write your own parser, or use an existing library. jQuery for example, takes care of this very well. Let's go back to our code. So we'll modify our code so that it outputs a list of speakers. We'll start by creating the output variable, just like we did with XML, and then in here we'll loop through the valleys of the objects.

To do that I am going to use the for in statement. Finally, we'll target the update element with the results of our output variable. So let's save this and switch back to our browser, refresh the page, and you can see that the list appears. So working with JSON files is pretty easy with the parse command. However, it might not be available in all browser versions. So for ultimate compatibility, I recommend that you use a library like jQuery.

There are currently no FAQs about JavaScript and AJAX.

 
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.
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.

join now 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
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

Notes cannot be added for locked videos.

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.