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JSON format supports the following data types −
| Sr.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 −
| Sr.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 −
| Sr.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;
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