Feature

XML

JSON

Language

XML is a markup language, not a programming language, that has tags to define elements.

JSON is just a format written in JavaScript.

Data Storage

XML data is stored as a tree structure. Example:

2001

 Varsha




 2002

 Akash

Data is stored like a map with key value pairs. Example:

{“employees”: [

 {"id":"2001", “name":"Varsha"}, 

 {"id":"2002", "name":"Akash"}

]}

Processing

Can perform processing, and formatting documents and objects

Does not do any processing or computation

Speed

Bulky and slow in parsing, leading to slower data transmission

Very fast as the size of file is considerably small, faster parsing by the JavaScript engine and hence faster transfer of data

Namespaces Support

Supports namespaces, comments and metadata

There is no provision for namespace, adding comments or writing metadata

Document Size

Document size is bulky and with big files, the tag structure makes it huge and complex to read.

Compact and easy to read, no redundant or empty tags or data, making the file look simple.

Array Support

Doesn’t directly support arrays. To be able to use an array, one has to add tags for each item.

Supports array

Data Types Support 

Supports many complex data types including charts, images, and other non-primitive data types.

JSON supports only strings, numbers, arrays, Booleans, and objects. Objects can only contain primitive types.

UTF Support

XML supports UTF-8 and UTF-16 encodings.

JSON supports UTF as well as ASCII encodings.

Security 

XML structures are prone to some attacks as external entity expansion and DTD validation are enabled by default. When these are disabled, XML parsers are safer.

JSON parsing is safe almost all the time except if JSONP is used, which can lead to Cross-Site Request Forgery (CSRF) attack.

Data Processing

Though the X in AJAX stands for XML, because of the tags in XML, a lot of bandwidth is unnecessarily consumed, making AJAX requests slow.

As data is serially processed in JSON, using it with AJAX ensures faster processing and is hence preferable. Data can be easily manipulated using the eval() method