Json - Datatypes
JSON format supports the following data types:
| Type | Description |
| Number | double- precision floating-point format in JavaScript |
| String | double-quoted Unicode with backslash escaping |
| Boolean | true or false |
| Array | an ordered sequence of values |
| Value | it can be a string, a number, true or false, null etc |
| Object | an unordered collection of key:value pairs |
| Whitespace | can be used between any pair of tokens |
| 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:
| Type | Description |
| Integer | Digits 1-9, 0 and positive or negative |
| Fraction | Fractions like .3, .9 |
| 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 string types:
| Type | Description |
| " | double quotation |
| \ | reverse solidus |
| / | solidus |
| b | backspace |
| f | form feed |
| n | new line |
| r | carriage return |
| t | horizontal tab |
| 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 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 a 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;
