Internal-ship Program : Improve knowledge about JavaScript Object Notation -DataTypes and Objects

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:

Creating Array Objects

Below example shows creation of an array object in javascript using JSON, save the below code asjson_array_object.htm:

<html>
<head>
<title>Creation of array object in javascript using JSON</title>
<script language="javascript" >

document.writeln("<h2>JSON array object</h2>");

var books = { "Pascal" : [ 
      { "Name"  : "Pascal Made Simple", "price" : 700 },
      { "Name"  : "Guide to Pascal", "price" : 400 }
   ],                       
   "Scala"  : [
      { "Name"  : "Scala for the Impatient", "price" : 1000 }, 
      { "Name"  : "Scala in Depth", "price" : 1300 }
   ]    
}    

var i = 0
document.writeln("<table border='2'><tr>");
for(i=0;i<books.Pascal.length;i++)
{ 
   document.writeln("<td>");
   document.writeln("<table border='1' width=100 >");
   document.writeln("<tr><td><b>Name</b></td><td width=50>"
   + books.Pascal[i].Name+"</td></tr>");
   document.writeln("<tr><td><b>Price</b></td><td width=50>"
   + books.Pascal[i].price +"</td></tr>");
   document.writeln("</table>");
   document.writeln("</td>");
}

for(i=0;i<books.Scala.length;i++)
{
   document.writeln("<td>");
   document.writeln("<table border='1' width=100 >");
   document.writeln("<tr><td><b>Name</b></td><td width=50>"
   + books.Scala[i].Name+"</td></tr>");
   document.writeln("<tr><td><b>Price</b></td><td width=50>"
   + books.Scala[i].price+"</td></tr>");
   document.writeln("</table>");
   document.writeln("</td>");
}
document.writeln("</tr></table>");
</script>
</head>
<body>
</body>
</html>

Now let's try to open json_array_object.htm using IE or any other javascript enabled browser, this produces the following result:

Internal-ship Program

Thursday, June 4, 2015

Improve knowledge about JavaScript Object Notation -DataTypes and Objects

Number

SYNTAX:

EXAMPLE:

String

SYNTAX:

EXAMPLE:

Boolean

SYNTAX:

EXAMPLE:

Array

SYNTAX:

EXAMPLE:

Object

SYNTAX:

EXAMPLE:

Whitespace

SYNTAX:

EXAMPLE:

null

SYNTAX:

EXAMPLE:

JSON Value

SYNTAX:

Creating Simple Objects

Creating Array Objects

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