JSON – DataTypes

S. No.	Type & Description
1	Number double- precision floating-point format in JavaScript
2	String double-quoted Unicode with backslash escaping
3	Boolean true or false
4	Array an ordered sequence of values
5	Value it can be a string, a number, true or false, null etc
6	Object an unordered collection of key:value pairs
7	Whitespace can be used between any pair of tokens
8	null empty

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 the number types –

The following table shows the number types −

S. No.	Type & Description
1	Integer Digits 1-9, 0 and positive or negative
2	Fraction Fractions like .3, .9
3	Exponent Exponent like e, e+, e-, E, E+, E-

 

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 various special characters that you can use in strings of a JSON document –

S. No.	Type & Description
1	" double quotation
2	\ backslash
3	/ forward slash
4	b backspace
5	f form feed
6	n new line
7	r carriage return
8	t horizontal tab
9	u four hexadecimal digits

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 in 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.

·        Objects are enclosed in curly braces that is, it starts with '{' and ends with '}'.

·        Each name is followed by ':'(colon) and the key/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 a code more readable. Example shows declaration with and without whitespace –

Syntax

{string:" ",....}

 

Example

var obj1 = {"name": "Sachin Tendulkar"}

var obj2 = {"name": "SauravGanguly"}

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;