Briefly about JSON

JSON: JavaScript Object Notation. JSON is a syntax for storing and exchanging data. JSON is an easier-to-use alternative to XML.

  • JSON stands for JavaScript Object Notation
  • JSON is a lightweight data-interchange format
  • JSON is language independent *
  • JSON is “self-describing” and easy to understand

JSON Example

    {"firstName":"John", "lastName":"Doe"},
    {"firstName":"Anna", "lastName":"Smith"},
    {"firstName":"Peter", "lastName":"Jones"}

XML Example

        <firstName>John</firstName> <lastName>Doe</lastName>
        <firstName>Anna</firstName> <lastName>Smith</lastName>
        <firstName>Peter</firstName> <lastName>Jones</lastName>
  • Both JSON and XML are “self describing” (human readable)
  • Both JSON and XML are hierarchical (values within values)
  • Both JSON and XML can be parsed and used by lots of programming languages
  • Both JSON and XML can be fetched with an XMLHttpRequest


  • JSON doesn’t use end tag
  • JSON is shorter
  • JSON is quicker to read and write
  • JSON can use arrays

Using XML

  • Fetch an XML document
  • Use the XML DOM to loop through the document
  • Extract values and store in variables

Using JSON

  • Fetch a JSON string
  • JSON.Parse the JSON string

JSON Syntax Rules

JSON syntax is derived from JavaScript object notation syntax:

  • Data is in name/value pairs
  • Data is separated by commas
  • Curly braces hold objects
  • Square brackets hold arrays

JSON Values

JSON values can be:

  • A number (integer or floating point)
  • A string (in double quotes)
  • A Boolean (true or false)
  • An array (in square brackets)
  • An object (in curly braces)
  • null

JSON Objects

JSON objects are written inside curly braces.

JSON Arrays

JSON arrays are written inside square brackets.

JSON Files

  • The file type for JSON files is “.json”
  • The MIME type for JSON text is “application/json”
// json example

var temp = {"student":[
    {"firstName":"John", "lastName":"Doe"},
    {"firstName":"Anna", "lastName":"Smith"},
    {"firstName":"Peter", "lastName":"Jones"}