Introduction to JSON (JavaScript Object Notation)

JSON, JavaScript Object Notation, is a very useful tool for AJAX developers (and many others I’m sure).

XML is fairly difficult for JavaScript to parse out.  It also includes quite a bit of infrastructure overhead in certain applications.  

Implementation of JSON can be very easy, it is imported natively in JavaScript through the eval() procedure.  It is also supported by many server side languages.

Lets take a basic example of an XML statement and see it’s JSON equivalent:

XML
<book id=”123″><author>Tom Jones</author></book>

JSON
{“book”: {“id”:”123″, “author”:”Tom Jones”}}

It may seem more cryptic, but if you look, that’s just because there are fewer iterations of key words.  The compression gets extended when you implement longer arrays of data.

The best part about JSON, in my opinion, is the speed increase you get when using it in javascript.  Please implement something in XML and JSON with the same data, you will notice a significant performance increase.

JSON is easy to consume in JavaScript:

objJSON = eval(jsonDataFeed);

You can access data (using our example earlier):

alert(objJSON.book.id);
alert(objJSON.book.author);

Server side implementation can be quite simple as well:

$dataObject = array();
$dataObject["book"] = array();
$dataObject["book"]["id"] = 123;
$dataObject["book"]["author"] = "Tom Jones";
echo (json_encode($dataObject));

Ask any questions in the comments below.  

Here are some articles to continue your exploration of JSON:

• How to use JSON
• Understanding JSON: the 3 minute lesson
• XML to JSON – a converter
• How to convert XML to JSON in ASP.NET C#
• Introducing JSON

Tags: AJAX, eval, Introduction, Javascript, Javascript Object Notation, JSON, Tutorials, XML