There are following datatypes supported by JSON format:
| 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 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 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
Creating Simple Objects
JSON objects can be created with Javascript. Let us see various ways of creating JSON objects using Javascript:
-
Creation of an empty Object:
var JSONObj = {};
-
Creation of new Object:
var JSONObj = new Object();
-
Creation of an object with attribute bookname with value in string, attribute price with numeric value. Attributes is accessed by using '.' Operator:
var JSONObj = { "bookname ":"VB BLACK BOOK", "price":500 };
This is an example which shows creation of an object in javascript using JSON, save the below code asjson_object.htm:
<html>
<head>
<title>Creating Object JSON with JavaScript</title>
<script language="javascript" >
var JSONObj = { "name" : "tutorialspoint.com", "year" : 2005 };
document.write("<h1>JSON with JavaScript example</h1>");
document.write("<br>");
document.write("<h3>Website Name="+JSONObj.name+"</h3>");
document.write("<h3>Year="+JSONObj.year+"</h3>");
</script>
</head>
<body>
</body>
</html>
Now let's try to open json_object.htm using IE or any other javascript enabled browser, this produces the following result:
Creation of an empty Object:
Creation of new Object:
Creation of an object with attribute bookname with value in string, attribute price with numeric value. Attributes is accessed by using '.' Operator:
