Web Designing: July 2010

Basic of JavaScript

Java Script Syntax and Features

1. There is no need to declare variable, however
you can

define variable with var keyword.

2. Curl braces ({}) are separated two code
blocks.

3. White space and carriage return are not count
in code statement.

4. Semicolon (;) terminate a statement.

5. For single line comment use double slash
(//).

6. For multi line comment use /* and */ sign.

Variable name rules

Variable are place holder of value used in run time by the program, every
variable has an unique name within the scope of execution, while declaring the
variable always keep un mind.

1. Must start with number and underscore (_)

2. Use any alphanumeric character.

3. Do not use any special character and white space.

4. Variable name are case sensitive.

5. Do not use keyword as variable name.

Operator and order of precedence

[]

()

>>>

<<=

>>=

>>>=

String
Operators

Concatenation

Comparison Operators

	==	Equal To
	!=	Not Equal To
	<	Less Than
	>	Greater Than
	>=	Greater than or equal to
	<=	Less than or equal to

Arithmetic Operators

	*	Multiplication
	/	Division
	+	Addition
	-	Subtraction

Logical
Operators

AND

Assignment
Operator

Assignment

Keyword List

In
JavaScript there are 50 keywords, this are reserve word in the language you can
not use this keyword in naming of variable or function.

abstract	float	public
boolean	for	return
break	function	short
byte	goto	static
case	if	super
catch	implements	switch
char	import	synchronized
class	in	this
const	instanceof	throw
continue	int	throws
default	interface	transient
do	long	true
double	native	try
else	new	var
extends	null	void
false	package	while
final	private	with
finally	protected

Conditional
Construct

1. if.. else ..

2. switch case

Looping Construct

1. for

2. while

User Define Function

function <functionname>(argument)

{

//function body

return <value>

}

Some Sample Small Programmes

1. Writing text on the browser window
<html>
<body>
<script language="JavaScript">
document.write("Hello World!")
</script>
</body>
</html>

2. Writing Formatted Text on the Browser
<html>
<body>
<script language="Java Script">
document.write("<h1>Hello World!</h1>")
</script>
</body>
</html>

3. Using HEAD Section
<html>
<head>
<script language="JavaScript">
function message(){
alert("This alert box was called with the onload
event")
}
</script>
</head>
<body onload="message()">
</body>
</html>

4. Using BODY Section
<html>
<head>
</head>
<body>
<script language="JavaScript">
document.write("This message is written when the
page loads")
</script>
</body>
</html>

<html>
<head>
</head>
<body>
<script src="myscript.js">
</script>
<p>The actual script is in an external script
file called "myscript.js".</p>
</body>
</html>

Try yourself.
1. Load any text editor (Notepad, WordPad, Word,
TextPlus)
2. Create the HTML file and save it, with .HTM or
.HTML extension. and write following HTML and javascrpt.
   <html>
   <body>
   <script language="JavaScript">
   document.write("Hello to JavaScript World!")
   </script>
   </body>
   </html>
3. Open saved file in Browser (IE, Netscape) to
view it will display Hello to JavaScript World!.

Java Scripting

What is Java Script?
JavaScript is an object-based scripting language designed primarily for HTML (Hypertext Markup Language), It supports both IE (internet Explorer) and Netscape Navigator and all other major web browser. Java script can be used for both client side as well as server side in web development. It is not a programming language it can not create executable code while compiling, it is embed in document and while pursing the html document it executes the script, it is an object-based scripting language, while reasonably simple in syntax, construction, and features, the object-based nature of JavaScript still offers programmers significant power and flexibility through the ability to create functions and new objects.
An object in the context of JavaScript, is a collection of properties and methods consisting a set of defined characteristics that you can view and modify, and which you can interact. Methods are the techniques that are used to perform action involving objects and properties. For example statement like Document. Write("Welcome to Javascript") here Document is the object, Write is the method of Document object, JavaScript follows event driven sequence. the events determine the program flow and event handlers determine what happen when these event occurs.

Where to Write Java Scrip
You can write javascript in body or head section depend on your requirement or you can write java script in a sepeate file with extension ".js" and includes it in your HTML document with

Saturday, July 3, 2010

Basic of JavaScript

Some Sample Small Programmes

Java Scripting