JSON - DataTypes

Hi Avnish,

There are following datatypes supported by JSON format:

Number

• It is a double precision floating-point format in JavaScript and it depends on implementation.

• Octal and hexadecimal formats are not used.

• No NaN or Infinity is used in Number.

The following table shows number types:

SYNTAX:

var json-object-name = { string : number_value, .......}

EXAMPLE:

Example showing Number Datatype, value should not be quoted:

var obj = {marks: 97}

String

• It is a sequence of zero or more double quoted Unicode characters with backslash escaping.

• Character is a single character string i.e. a string with length 1.

The table shows string types:

SYNTAX:

var json-object-name = { string : "string value", .......}

EXAMPLE:

Example showing String Datatype:

var obj = {name: 'Amit'}

Boolean

It includes true or false values.

SYNTAX:

var json-object-name = { string : true/false, .......}

EXAMPLE:

var obj = {name: 'Amit', marks: 97, distinction: true}

Array

• It is an ordered collection of values.

•  

  These are enclosed square brackets which means that array begins with .[. and ends with .]..

• The values are separated by ,(comma).

• Array indexing can be started at 0 or 1.

• Arrays should be used when the key names are sequential integers.

SYNTAX:

[ value, .......]

EXAMPLE:

Example showing array containing multiple objects:

{
  "books": [
   { "language":"Java" , "edition":"second" },
   { "language":"C++" , "lastName":"fifth" },
   { "language":"C" , "lastName":"third" }
  ]
}

Object

• It is an unordered set of name/value pairs.

• Object are enclosed in curly braces that is it starts with '{' and ends with '}'.

• Each name is followed by ':'(colon) and the name/value pairs are separated by , (comma).

• The keys must be strings and should be different from each other.

• Objects should be used when the key names are arbitrary strings

SYNTAX:

{ string : value, .......}

EXAMPLE:

Example showing Object:

{
 "id": "011A",
 "language": "JAVA",
 "price": 500,
}

Whitespace

It can be inserted between any pair of tokens. It can be added to make code more readable. Example shows declaration with and without whitespace:

SYNTAX:

{string:"   ",....}

EXAMPLE:

var i= "   sachin";
var j = "  saurav"

null

It means empty type.

SYNTAX:

null

EXAMPLE:

var i = null;

if(i==1) 
{
   document.write("<h1>value is 1</h1>");	
}
else
{
   document.write("<h1>value is null</h1>");
}

JSON Value

It includes:

• number (integer or floating point)

• string

• boolean

• array

• object

• null

SYNTAX:

String | Number | Object | Array | TRUE | FALSE | NULL

EXAMPLE:

var i =1;
var j = "sachin";
var k = null;