Java scripts

How to Handle Simple Browsers ::
-----------------------------------------
Browsers that do not support JavaScript, will display JavaScript as page content.

To prevent them from doing this, and as a part of the JavaScript standard, the HTML comment tag should
be used to "hide" the JavaScript.

Just add an HTML comment tag  (end of comment)
after the last JavaScript statement, like this:
<html>
<body>
<script type="text/javascript">

</script>
</body>
</html>

The two forward slashes at the end of comment line (//) is the JavaScript comment symbol. This prevents
JavaScript from executing the --> tag.

JavaScript Where To
================

JavaScripts in the body section will be executed WHILE the page loads.

JavaScripts in the head section will be executed when CALLED.
Where to Put the JavaScript

JavaScripts in a page will be executed immediately while the page loads into the browser. This is not
always what we want. Sometimes we want to execute a script when a page loads, other times when a
user triggers an event.
Scripts in <head>

Scripts to be executed when they are called, or when an event is triggered, go in the head section.

If you place a script in the head section, you will ensure that the script is loaded before anyone uses it.
Example
<html>
<head>
function message()
{
alert("This alert box was called with the onload event"); //It is used to show the Messagebox with content
}
</script>
</head>

<body onload="message()">
</body>
</html>

Scripts in <body>

===============
Scripts to be executed when the page loads go in the body section.

If you place a script in the body section, it generates the content of a page.
Example
<html>
<head>
</head>

<body>
document.write("This message is written by JavaScript");
</script>
</body>

</html>

Scripts in <head> and <body>
=======================
You can place an unlimited number of scripts in your document, so you can have scripts in both the body
and the head section.
<html>
<head>
....
</script>
</head>
<body>
....
</script>
</body>

Using an External JavaScript
===================
If you want to run the same JavaScript on several pages, without having to write the same script on every
page, you can write a JavaScript in an external file.

Save the external JavaScript file with a .js file extension.

Note: The external script cannot contain the <script> tag!

To use the external script, point to the .js file in the "src" attribute of the <script> tag:
Example
<html>
<head>
<script type="text/javascript" src="xxx.js"></script>
</head>
<body>
</body>
</html>
Note: Remember to place the script exactly where you normally would write the script!

****
The semicolon is optional (according to the JavaScript standard), and the browser is supposed to

interpret the end of the line as the end of the statement. Because of this you will often see examples
without the semicolon at the end.

Note: Using semicolons makes it possible to write multiple statements on one line.

JavaScript Blocks
============
JavaScript statements can be grouped together in blocks.

Blocks start with a left curly bracket {, and ends with a right curly bracket }.

The purpose of a block is to make the sequence of statements execute together.

This example will write a heading and two paragraphs to a web page:
Example
{
document.write("<h1>This is a heading</h1>");
document.write("<p>This is a paragraph.</p>");
document.write("<p>This is another paragraph.</p>");
}
</script>

Declaring (Creating) JavaScript Variables
============================
Creating variables in JavaScript is most often referred to as "declaring" variables.

You can declare JavaScript variables with the var statement:
var x;
var carname;

After the declaration shown above, the variables are empty (they have no values yet).

However, you can also assign values to the variables when you declare them:
var x=5;
var carname="Volvo";

After the execution of the statements above, the variable x will hold the value 5, and carname will hold the
value Volvo.

Note: When you assign a text value to a variable, use quotes around the value.
Assigning Values to Undeclared JavaScript Variables

If you assign values to variables that have not yet been declared, the variables will automatically be
declared.

These statements:
x=5;
carname="Volvo";

have the same effect as:
var x=5;
var carname="Volvo";

Redeclaring JavaScript Variables
=======================

If you redeclare a JavaScript variable, it will not lose its original value.
var x=5;
var x;

After the execution of the statements above, the variable x will still have the value of 5. The value of x is
not reset (or cleared) when you redeclare it.
JavaScript Arithmetic

As with algebra, you can do arithmetic operations with JavaScript variables:
y=x-5;
z=y+5;

The + Operator Used on Strings
=======================
The + operator can also be used to add string variables or text values together.

To add two or more string variables together, use the + operator.
txt1="What a very";
txt2="nice day";
txt3=txt1+txt2;

After the execution of the statements above, the variable txt3 contains "What a verynice day".

To add a space between the two strings, insert a space into one of the strings:
txt1="What a very ";
txt2="nice day";
txt3=txt1+txt2;

or insert a space into the expression:
txt1="What a very";
txt2="nice day";
txt3=txt1+" "+txt2;

After the execution of the statements above, the variable txt3 contains:

"What a very nice day"
Example :-
<html>
<body>

x=5+5;
document.write(x);
document.write("<br />");
x="5"+"5";
document.write(x);
x=5+"5";
document.write(x);
x="5"+5;
document.write(x);
</script>

<p>The rule is: If you add a number and a string, the result will be a string.</p>

</body>
</html>

Output :-
10
55
55
55

The rule is: If you add a number and a string, the result will be a string.

JavaScript Comparison and Logical Operators
===============================

Comparison and Logical operators are used to test for true or false.
Comparison Operators

Comparison operators are used in logical statements to determine equality or difference between
variables or values.

Given that x=5, the table below explains the comparison operators:
Operator Description Example
== is equal to x==8 is false
=== is exactly equal to (value and type) x===5 is true
x==="5" is false
!= is not equal x!=8 is true
> is greater than x>8 is false
< is less than x<8 is true
>= is greater than or equal to x>=8 is false
<= is less than or equal to x<=8 is true

How Can it be Used

Comparison operators can be used in conditional statements to compare values and take action
depending on the result:
if (age<18) document.write("Too young");

You will learn more about the use of conditional statements in the next chapter of this tutorial.
Logical Operators

Logical operators are used to determine the logic between variables or values.

Given that x=6 and y=3, the table below explains the logical operators:
Operator Description Example
&& and (x < 10 && y > 1) is true
|| or (x==5 || y==5) is false
! not !(x==y) is true

Conditional Operator

JavaScript also contains a conditional operator that assigns a value to a variable based on some
condition.
Syntax
variablename=(condition)?value1:value2

Example
greeting=(visitor=="PRES")?"Dear President ":"Dear "; //No Space

If the variable visitor has the value of "PRES", then the variable greeting will be assigned the value "Dear
President " else it will be assigned "Dear".

JavaScript If...Else Statements
========================

* if statement - use this statement to execute some code only if a specified condition is true
* if...else statement - use this statement to execute some code if the condition is true and another code
if the condition is false
* if...else if....else statement - use this statement to select one of many blocks of code to be executed
* switch statement - use this statement to select one of many blocks of code to be executed

Example :
if and if else ::
if (condition)
{
code to be executed if condition is true
}
else
{
code to be executed if condition is not true
}

if else if ::
if (condition1)
{
code to be executed if condition1 is true
}
else if (condition2)
{
code to be executed if condition2 is true
}
else
{
code to be executed if condition1 and condition2 are not true
}

Swich Case ::
switch (favoritemovie){
case "Titanic":
alert("Not a bad choice!")
break;
case "Water World":
alert("No comment")
break;
case "Scream 2":
alert("It has its moments")
break;
default : alert("I'm sure it was great");
}

JavaScript Popup Boxes

Alert Box
======================
JavaScript has three kind of popup boxes: Alert box, Confirm box, and Prompt box.
Alert Box

An alert box is often used if you want to make sure information comes through to the user.

When an alert box pops up, the user will have to click "OK" to proceed.
Syntax
alert("sometext");

Example
<html>
<head>
function show_alert()
{
alert("I am an alert box!");
}
</script>
</head>
<body>

<input type="button" onclick="show_alert()" value="Show alert box" />

</body>
</html>

Confirm Box
=========================
A confirm box is often used if you want the user to verify or accept something.

When a confirm box pops up, the user will have to click either "OK" or "Cancel" to proceed.

If the user clicks "OK", the box returns true. If the user clicks "Cancel", the box returns false.
Syntax
confirm("sometext");

Example
<html>
<head>
function show_confirm()
{
var r=confirm("Press a button");
if (r==true)
{
document.write("You pressed OK!");
}
else
{
document.write("You pressed Cancel!");
}

}
</script>
</head>
<body>

<input type="button" onclick="show_confirm()" value="Show confirm box" />

</body>
</html>

Prompt Box
===========================
A prompt box is often used if you want the user to input a value before entering a page.

When a prompt box pops up, the user will have to click either "OK" or "Cancel" to proceed after entering
an input value.

If the user clicks "OK" the box returns the input value. If the user clicks "Cancel" the box returns null.
Syntax
prompt("sometext","defaultvalue");

Example
<html>
<head>
function show_prompt()
{
var name=prompt("Please enter your name","Harry Potter");
if (name!=null && name!="")
{
document.write("Hello " + name + "! How are you today?");
}
}
</script>
</head>
<body>

<input type="button" onclick="show_prompt()" value="Show prompt box" />

</body>
</html>

Function :::
===============
word function is in lower case
with no parameter
<html>
<head>
function displaymessage()
{
alert("Hello World!");
}
</script>
</head>

<body>
<form>
<input type="button" value="Click me!" onclick="displaymessage()" />
</form>
</body>
</html>

Function with return Type :

<html>
<head>
function product(a,b)
{
return a*b;
}
</script>
</head>

<body>
document.write(product(4,3));
</script>

</body>
</html>

The for Loop
=========
<html>
<body>
var i=0;
for (i=0;i<=5;i++)
{
document.write("The number is " + i);
}
</script>
</body>
</html>

While Loop
========

<html>
<body>
var i=0;
while (i<=5)
{
i++;
}

</script>
</body>
</html>

Do-While Lop
============
<html>
<body>
var i=0;
do
{
i++;
}
while (i<=5);
</script>
</body>

The break Statement
====================

The break statement will break the loop and continue executing the code that follows after the loop (if
any).
Example
<html>
<body>
var i=0;
for (i=0;i<=10;i++)
{
if (i==3)
{
break;
}
}
</script>
</body>
</html>

The continue Statement
=======================

The continue statement will break the current loop and continue with the next value.
Example
<html>
<body>
var i=0
for (i=0;i<=10;i++)
{

if (i==3)
{
continue;
}
}
</script>
</body>
</html>

JavaScript For...In Statement(For each Loop)
=====================
The for...in statement loops through the elements of an array or through the properties of an object.
Syntax
for (variable in object)
{
code to be executed
}

Note: The code in the body of the for...in loop is executed once for each element/property.

Note: The variable argument can be a named variable, an array element, or a property of an object.
Example

Use the for...in statement to loop through an array:
Example
<html>
<body>

var x;
var mycars = new Array();
mycars[0] = "Saab";
mycars[1] = "Volvo";
mycars[2] = "BMW";

for (x in mycars)
{
document.write(mycars[x] + "<br />");
}
</script>

</body>
</html>

Events (http://www.w3schools.com/jsref/jsref_events.asp) All events with discription
=======================
By using JavaScript, we have the ability to create dynamic web pages. Events are actions that can be
detected by JavaScript.

Every element on a web page has certain events which can trigger a JavaScript. For example, we can
use the onClick event of a button element to indicate that a function will run when a user clicks on the
button. We define the events in the HTML tags.

Examples of events:

* A mouse click
* A web page or an image loading
* Mousing over a hot spot on the web page
* Selecting an input field in an HTML form
* Submitting an HTML form
* A keystroke

Note: Events are normally used in combination with functions, and the function will not be executed
before the event occurs!

For a complete reference of the events recognized by JavaScript, go to our complete Event reference.
onLoad and onUnload

The onLoad and onUnload events are triggered when the user enters or leaves the page.

The onLoad event is often used to check the visitor's browser type and browser version, and load the
proper version of the web page based on the information.

Both the onLoad and onUnload events are also often used to deal with cookies that should be set when a
user enters or leaves a page. For example, you could have a popup asking for the user's name upon his
first arrival to your page. The name is then stored in a cookie. Next time the visitor arrives at your page,
you could have another popup saying something like: "Welcome John Doe!".
onFocus, onBlur and onChange

The onFocus, onBlur and onChange events are often used in combination with validation of form fields.

Below is an example of how to use the onChange event. The checkEmail() function will be called
whenever the user changes the content of the field:
<input type="text" size="30" id="email" onchange="checkEmail()">

onSubmit

The onSubmit event is used to validate ALL form fields before submitting it.

Below is an example of how to use the onSubmit event. The checkForm() function will be called when the
user clicks the submit button in the form. If the field values are not accepted, the submit should be
cancelled. The function checkForm() returns either true or false. If it returns true the form will be
submitted, otherwise the submit will be cancelled:
<form method="post" action="xxx.htm" onsubmit="return checkForm()">

onMouseOver and onMouseOut

onMouseOver and onMouseOut are often used to create "animated" buttons.

Below is an example of an onMouseOver event. An alert box appears when an onMouseOver event is
detected:
<a href="http://www.w3schools.com" onmouseover="alert('An onMouseOver event');return false"><img
src="w3s.gif" alt="W3Schools" /></a>

JavaScript - Catching Errors(Try.............catch Statement)
===============================
When browsing Web pages on the internet, we all have seen a JavaScript alert box telling us there is a

runtime error and asking "Do you wish to debug?". Error message like this may be useful for developers
but not for users. When users see errors, they often leave the Web page.

This chapter will teach you how to catch and handle JavaScript error messages, so you don't lose your
audience.
The try...catch Statement

The try...catch statement allows you to test a block of code for errors. The try block contains the code to
be run, and the catch block contains the code to be executed if an error occurs.
Syntax
try
{
//Run some code here
}
catch(err)
{
//Handle errors here
}

Note that try...catch is written in lowercase letters. Using uppercase letters will generate a JavaScript
error!
Example 1

The example below is supposed to alert "Welcome guest!" when the button is clicked. However, there's a
typo in the message() function. alert() is misspelled as adddlert(). A JavaScript error occurs. The catch
block catches the error and executes a custom code to handle it. The code displays a custom error
message informing the user what happened:
Example
<html>
<head>
var txt=""
function message()
{
try
{
adddlert("Welcome guest!");
}
catch(err)
{
txt="There was an error on this page.nn";
txt+="Error description: " + err.description + "nn";
txt+="Click OK to continue.nn";
alert(txt);
}
}
</script>
</head>

<body>
<input type="button" value="View message" onclick="message()" />
</body>

</html>

The next example uses a confirm box to display a custom message telling users they can click OK to

continue viewing the page or click Cancel to go to the homepage. If the confirm method returns false, the
user clicked Cancel, and the code redirects the user. If the confirm method returns true, the code does
nothing:

Example
<html>
<head>
var txt=""
function message()
{
try
{
adddlert("Welcome guest!");
}
catch(err)
{
txt="There was an error on this page.nn";
txt+="Click OK to continue viewing this page,n";
txt+="or Cancel to return to the home page.nn";
if(!confirm(txt))
{
document.location.href="http://www.w3schools.com/";
}
}
}
</script>
</head>

<body>
<input type="button" value="View message" onclick="message()" />
</body>

</html>

JavaScript Special Characters
===========================

In JavaScript you can add special characters to a text string by using the backslash sign.
Insert Special Characters

The backslash () is used to insert apostrophes, new lines, quotes, and other special characters into a text
string.

Look at the following JavaScript code:
var txt="We are the so-called "Vikings" from the north.";
document.write(txt);

In JavaScript, a string is started and stopped with either single or double quotes. This means that the
string above will be chopped to: We are the so-called

To solve this problem, you must place a backslash () before each double quote in "Viking". This
turns each double quote into a string literal:
var txt="We are the so-called "Vikings" from the north.";
document.write(txt);

JavaScript will now output the proper text string: We are the so-called "Vikings" from the north.

Here is another example:
document.write ("You & I are singing!");

The example above will produce the following output:
You & I are singing!

The table below lists other special characters that can be added to a text string with the backslash sign:
Code Outputs
' single quote
" double quote
& ampersand
backslash
n new line
r carriage return
t tab
b backspace
f form feed

JavaScript Guidelines
============================

Some other important things to know when scripting with JavaScript.
JavaScript is Case Sensitive

A function named "myfunction" is not the same as "myFunction" and a variable named "myVar" is not the
same as "myvar".

JavaScript is case sensitive - therefore watch your capitalization closely when you create or call variables,
objects and functions.
White Space

JavaScript ignores extra spaces. You can add white space to your script to make it more readable.
The following lines are equivalent:
name="Hege";
name = "Hege";

Break up a Code Line

You can break up a code line within a text string with a backslash. The example below will be displayed
properly:
document.write("Hello
World!");

However, you cannot break up a code line like this:
document.write
("Hello World!");

JavaScript Objects Introduction
=============================

previous next

JavaScript is an Object Oriented Programming (OOP) language.

An OOP language allows you to define your own objects and make your own variable types.
Object Oriented Programming

JavaScript is an Object Oriented Programming (OOP) language. An OOP language allows you to define
your own objects and make your own variable types.

Properties

Properties are the values associated with an object.

In the following example we are using the length property of the String object to return the number of
characters in a string:
var txt="Hello World!";
document.write(txt.length);
</script>

The output of the code above will be:
12


JavaScript is an Object Oriented Programming (OOP) language.

An OOP language allows you to define your own objects and make your own variable types.
Object Oriented Programming

JavaScript is an Object Oriented Programming (OOP) language. An OOP language allows you to define
your own objects and make your own variable types.

However, creating your own objects will be explained later, in the Advanced JavaScript section. We will
start by looking at the built-in JavaScript objects, and how they are used. The next pages will explain each
built-in JavaScript object in detail.

Note that an object is just a special kind of data. An object has properties and methods.

Properties
==================
Properties are the values associated with an object.

In the following example we are using the length property of the String object to return the number of
characters in a string:
document.write(txt.length);
</script>

12

Methods
================
Methods are the actions that can be performed on objects.

In the following example we are using the toUpperCase() method of the String object to display a text in
uppercase letters:
var str="Hello world!";
document.write(str.toUpperCase());
</script>

HELLO WORLD!

String Functions :
=================

<html>
<body>



document.write("<p>Big: " + txt.big() + "</p>"); O/p Big: Hello World!
document.write("<p>Small: " + txt.small() + "</p>"); O/p :Small: Hello
World!

document.write("<p>Bold: " + txt.bold() + "</p>"); O/p :Bold: Hello
World!
document.write("<p>Italic: " + txt.italics() + "</p>"); O/p :Italic: Hello
World!

document.write("<p>Blink: " + txt.blink() + " (does not work in IE)</p>"); O/p :Blink: Hello
World! (does not work in IE) //here Hello World will continue blink !
document.write("<p>Fixed: " + txt.fixed() + "</p>"); O/p: Fixed: Hello World!
document.write("<p>Strike: " + txt.strike() + "</p>"); O/P:Strike: Hello
World!

document.write("<p>Fontcolor: " + txt.fontcolor("Red") + "</p>"); O/P:Fontsize: Hello
World!
document.write("<p>Fontsize: " + txt.fontsize(16) + "</p>"); Lowercase: hello
world!

document.write("<p>Lowercase: " + txt.toLowerCase() + "</p>"); Uppercase: HELLO
WORLD!
document.write("<p>Uppercase: " + txt.toUpperCase() + "</p>");

document.write("<p>Subscript: " + txt.sub() + "</p>"); Subscript: Hello World!
// O/p is not shown in wordpad properly

document.write("<p>Superscript: " + txt.sup() + "</p>"); Superscript: Hello
World! //O/p is not shown in wordpad properly

document.write("<p>Link: " + txt.link("http://www.w3schools.com") + "</p>"); Link: Hello World
//Now it becomes link now
</script>

</body>
</html>

<html>
<body>

String always starts from zero(0)

index function
=============
document.write(str.indexOf("Hello") + "<br />"); O/p : 1
document.write(str.indexOf("World") + "<br />"); O/p : -1(because "W" not found its is
"w")
document.write(str.indexOf("world")); O/p : 6
</script>

</body>
</html>

match function
=========
It will return string/string portion whereever it will be found .........return null if not match
<html>
<body>

document.write(str.match("world") + "<br />"); world
document.write(str.match("World") + "<br />"); null
document.write(str.match("worlld") + "<br />"); null
document.write(str.match("world!")); world!
</script>

</body>
</html>

Replace Function
===============
it will replace string
it is necessary to pass the Forward slash in the starting and in the end of string that is need to
replace

<html>
<body>


this.jobtitle=jobtitle;
this.born=born;
}

var fred=new employee("Fred Flintstone","Caveman",1970): /// employee is not the class while even
we can creates its object and assign the values to its property and create too.
employee.prototype.salary=null; /// created new property
fred.salary=20000;

document.write(fred.salary);

</script>

20000

The anchor() method is used to create an HTML anchor. ::::::::::::::::::::::::
Syntax
stringObject.anchor(anchorname)

Parameter Description
anchorname Required. Defines a name for the anchor

Example

In this example we will add an anchor to a text:

var txt="Hello world!";
document.write(txt.anchor("myanchor"));

</script>

The code above could be written in plain HTML, like this:
<a name="myanchor">Hello world!</a>

The charAt() method returns the character at a specified position::::::::::::::::::::::::::::::::::
Syntax
stringObject.charAt(index)

index Required. A number representing a position in the string

Tips and Notes

Note: The first character in the string is at position 0.
Example

In the string "Hello world!", we will return the character at position 1:

document.write(str.charAt(1));

</script>

e

The charCodeAt() method returns the Unicode of the character at a specified position::::::::::::::::::::::
Syntax
stringObject.charCodeAt(index)

index Required. A number representing a position in the string

Tips and Notes

Note: The first character in the string is at position 0.
Example

In the string "Hello world!", we will return the Unicode of the character at position 1:

document.write(str.charCodeAt(1));

</script>

101

The concat() method is used to join two or more strings.::::::::::::::::::::::::
Syntax
stringObject.concat(stringX,stringX,...,stringX)

stringX Required. One or more string objects to be joined to a string

Example

In the following example we will create two strings and show them as one using concat():

var str1="Hello ";
var str2="world!";
document.write(str1.concat(str2));

</script>

Hello world!

The fromCharCode() takes the specified Unicode values and returns a string.:::::::::::::::::::
Syntax
String.fromCharCode(numX,numX,...,numX)

numX Required. One or more Unicode values

Tips and Notes

Note: This method is a static method of String - it is not used as a method of a String object that
you have created. The syntax is always String.fromCharCode() and not
myStringObject.fromCharCode().
Example

In this example we will write "HELLO" and "ABC" from Unicode:

document.write(String.fromCharCode(72,69,76,76,79));
document.write(String.fromCharCode(65,66,67));

</script>

HELLO
ABC

The lastIndexOf() method returns the position of the last occurrence of a specified string value,
searching backwards from the specified position in a string.::::::
Syntax
stringObject.lastIndexOf(searchvalue,fromindex)

search Required. Specifies a string value to search for
fromindex Optional. Specifies where to start the search. Starting backwards in the string

Tips and Notes

Note: The lastIndexOf() method is case sensitive!

Note: This method returns -1 if the string value to search for never occurs.
Example

In this example we will do different searches within a "Hello world!" string:

document.write(str.lastIndexOf("Hello") + "<br />");
document.write(str.lastIndexOf("World") + "<br />");
document.write(str.lastIndexOf("world"));

</script>

0
-1
6

The search() method is used to search a string for a specified value.::::::::::::::::

This method supports regular expressions. You can learn about the RegExp object in our JavaScript
tutorial.
Syntax
stringObject.search(searchstring)

searchstring Required. The value to search for in a string. To perform a case-insensitive search add
an 'i' flag

Tips and Notes

Note: search() is case sensitive.

Note: The search() method returns the position of the specified value in the string. If no match was found
it returns -1.
Example 1 - Standard Search

In the following example we will search for the word "W3Schools":

var str="Visit W3Schools!";
document.write(str.search(/W3Schools/));

</script>

6

Note: In the following example the word "w3schools" will not be found (because the search()
method is case sensitive):

var str="Visit W3Schools!";
document.write(str.search(/w3schools/));

</script>

-1

The slice() method extracts a part of a string and returns the extracted part in a new
string.::::::::::::::::::

Syntax
stringObject.slice(start,end) /// It is based on position not on length unlike substring(based on
length see below)

start Required. Specify where to start the selection. Must be a number. Starts at 0
end Optional. Specify where to end the selection. Must be a number

Tips and Notes

Tip: You can use negative index numbers to select from the end of the string.

Note: If end is not specified, slice() selects all characters from the specified start position and to the end of
the string.
Example 1

In this example we will extract all characters from a string, starting at position 0:

var str="Hello happy world!";
document.write(str.slice(0));

</script>

Hello happy world!

Example 2

In this example we will extract all characters from a string, starting at position 6:

document.write(str.slice(6));

</script>

happy world!

Example 3

In this example we will extract only the first character from a string:

document.write(str.slice(0,1));

</script>

H

The split() method is used to split a string into an array of strings.::::::::::::;;
Syntax
stringObject.split(separator, howmany)

separator Required. Specifies the character, regular expression, or substring that is used to
determine where to split the string
howmany Optional. Specify how many times split should occur. Must be a numeric value

Tips and Notes

Note: If an empty string ("") is used as the separator, the string is split between each character.
Example

In this example we will split up a string in different ways:

var str="How are you doing today?";

document.write(str.split(" ") + "<br />");
document.write(str.split("") + "<br />");
document.write(str.split(" ",3));

</script>

How,are,you,doing,today?
H,o,w, ,a,r,e, ,y,o,u, ,d,o,i,n,g, ,t,o,d,a,y,?
How,are,you

The substr() method extracts a specified number of characters in a string, from a start
index.:::::::::::
Syntax
stringObject.substr(start,length)

start Required. Where to start the extraction. Must be a numeric value
length Optional. How many characters to extract. Must be a numeric value.

Tips and Notes

Note: To extract characters from the end of the string, use a negative start number (This does not work in
IE).

Note: The start index starts at 0.

Note: If the length parameter is omitted, this method extracts to the end of the string.
Example 1

In this example we will use substr() to extract some characters from a string:

document.write(str.substr(3));

</script>

lo world!

Example 2

In this example we will use substr() to extract some characters from a string:

document.write(str.substr(3,7)); // Start from 3 and count 7 characters from there

</script>

lo worl

Java Script Regular Expression :
==========================
JavaScript global Property ::::

JavaScript global Property
RegExp Object Reference Complete RegExp Object Reference
Definition and Usage

The global property is used to return whether or not the "g" modifier is used in the regular expression.

The "g" modifier is set if the regular expression should be tested against all possible matches in the string.

This property is "TRUE" if the "g" modifier is set, "FALSE" otherwise.
Syntax
RegExpObject.global

<html>
<body>

var str = "Visit W3Schools";
var patt1 = new RegExp("s","g");

if(patt1.global)
{
document.write("Global property is set");
}
else
{
document.write("Global property is NOT set.");
}
</script>

</body>
</html>
o/p Global property is set

JavaScript ignoreCase Property

JavaScript ignoreCase Property
RegExp Object Reference Complete RegExp Object Reference
Definition and Usage

The ignoreCase property is used to return whether or not the "i" modifier is used in the regular
expression.

The "i" modifier is set if the regular expression should ignore the case of characters.

This property is "TRUE" if the "i" modifier is set, "FALSE" otherwise.
Syntax
RegExpObject.ignoreCase

<html>
<body>

var patt1 = new RegExp("S","i");

if(patt1.ignoreCase)
{
document.write("ignoreCase property is set");
}
else
{
document.write("ignoreCase property is NOT set.");
}
</script>

</body>
</html>
o/p=ignoreCase property is set

JavaScript input Property

The input property is the string the pattern match is performed.
<html>
<body>

function getRegInput()
{
var patt1 = new RegExp("W3");
var str = document.frm1.txtinput.value;
patt1.test(str); ///????

if(RegExp.input)
{
alert("The input is: " + RegExp.input);
}
else
{
alert("The input does not contain W3");
}
}
</script>

<form name="frm1">
Enter some text and click outside:
<input type="text" name="txtinput" onChange='getRegInput()' /><br />
Input will only show if text contains W3.
</form>

</body>
</html>

JavaScript lastIndex Property
The lastIndex property specifies the index (placement) in the string where to start the next match.

The index is a number specifying the placement of the first character after the last match.

This property only works if the "g" modifier is set.
Syntax
RegExpObject.lastIndex

<html>
<body>

var str = "The rain in Spain stays mainly in the plain";
var patt1 = new RegExp("ain", "g");
for(i = 0; i < 4; i++)
{
patt1.test(str);
document.write("ain found. index now at: " + patt1.lastIndex);
}
</script>

</body>
</html>

Output :
ain found. index now at: 8

JavaScript lastMatch Property

The lastMatch property is the last matched characters.
Syntax
RegExp.lastMatch

<html>
<body>

for(i = 0; i < 4; i++)
{
patt1.test(str);
document.write(RegExp.lastMatch);
// document.write(" found. index now at: " + patt1.lastIndex);
}
</script>

</body>
</html>

o/p
ain
ain
ain
ain

JavaScript leftContext Property(Nice)

The leftContext property is the substring in front of the characters most recently matched.

This property contains everything from the string from before the match.
Syntax
RegExp.leftContext

<html>
<body>

for(i = 0; i < 4; i++)
{
patt1.test(str)
document.write(" found. Text before match: " + RegExp.leftContext);
}
</script>

</body>
</html>

o/p :
ain found. Text before match: The r
ain found. Text before match: The rain in Sp
ain found. Text before match: The rain in Spain stays m
ain found. Text before match: The rain in Spain stays mainly in the pl

JavaScript multiline Property

The multiline property is used to return whether or not the "m" modifier is used in the regular expression.

The "m" modifier is set if the regular expression should be tested against possible matches over multiple
lines.

This property is "TRUE" if the "m" modifier is set, "FALSE" otherwise.
Syntax
RegExpObject.multiline
<html>
<body>

<body>

var patt1 = new RegExp("W3S","g");

document.write("The regular expression is: " + patt1.source);
</script>

</body>
</html>
o/p::The regular expression is: W3S

JavaScript compile() Method

The compile() method is used to change the regular expression.
Syntax
RegExpObject.compile(regexp)

regexp Required. The new regular expression to search for

Example

In the following example we change the pattern from "Microsoft" to "W3Schools", and then test if we find
the specified pattern in a string:
var str="Visit W3Schools";
var patt=new RegExp("Microsoft");

document.write("Test if we find " + patt + " in " + str + ": ")

if (patt.test(str)==true)
{
document.write("Match found!")
}
else
{
document.write("Match not found")
}

patt.compile("W3Schools");

document.write("<br />")

{
}
else
{
}

</script>

Test if we find /Microsoft/ in Visit W3Schools: Match not found
Test if we find /W3Schools/ in Visit W3Schools: Match found!

JavaScript exec() Method

The exec() method searches a string for a specified value.

This method returns the matched text if a match is found, and null if not.
Syntax
RegExpObject.exec(string)

RegExpObject Required. The regular expression to use
string Required. The string to search

Example

In the following example we will search for "W3Schools" in a string:

var patt=new RegExp("W3Schools");

document.write(patt.exec(str));

</script>

W3Schools

JavaScript test() Method
The test() method searches a string for a specified value.

This method returns true if a match is found, and false if not.
Syntax
RegExpObject.test(string)

RegExpObject Required. The regular expression to use
string Required. The string to search

Example

In the following example we change the pattern from "Microsoft" to "W3Schools", and then test if we find
the specified pattern in a string:

var patt=new RegExp("Microsoft");


{
}
else
{
}

patt.compile("W3Schools");

document.write("<br />")

{
}
else
{
}

</script>

Test if we find /Microsoft/ in Visit W3Schools: Match not found
Test if we find /W3Schools/ in Visit W3Schools: Match found!

JavaScript isFinite() Function

The isFinite() function is used to check if a value is a finite number.
Syntax
isFinite(number)

number Required. The value to be tested

Example

In this example we use isFinite() to check for finite numbers:

document.write(isFinite(123)+ "<br />");
document.write(isFinite(-1.23)+ "<br />");
document.write(isFinite(5-2)+ "<br />");
document.write(isFinite(0)+ "<br />");
document.write(isFinite("Hello")+ "<br />");
document.write(isFinite("2005/12/12")+ "<br />");

</script>

true
true
true
true
false
false

JavaScript Number() Function

The Number() function converts the value of an object to a number.
Syntax
Number(object)

object Required. A JavaScript object

Tips and Notes

Note: If the parameter is a Date object, the Number() function returns the number of milliseconds
since midnight January 1, 1970 UTC.

Note: If the object's value cannot be converted to a number, the Number() function returns NaN.
Example

In this example we will try to convert different objects to numbers:

var test1= new Boolean(true);
var test2= new Boolean(false);
var test3= new Date();
var test4= new String("999");
var test5= new String("999 888");

document.write(Number(test1)+ "<br />");

</script>

1
0
1247394276301
999
NaN

JavaScript isNaN() Function

The isNaN() function is used to check if a value is not a number.
Syntax

isNaN(number)

number Required. The value to be tested

Example

In this example we use isNaN() to check some values:

document.write(isNaN(123)+ "<br />");
document.write(isNaN(-1.23)+ "<br />");
document.write(isNaN(5-2)+ "<br />");
document.write(isNaN(0)+ "<br />");
document.write(isNaN("Hello")+ "<br />");
document.write(isNaN("2005/12/12")+ "<br />");

</script>

false
false
false
false
true
true

JavaScript escape() Function

The escape() function encodes a string, so it can be read on all computers.
Syntax
escape(string)

string Required. The string to be encoded

Tips and Notes

Note: The escape() function encodes special characters, with the exception of:
*@-_+./

Tip: Use the unescape() function to decode strings encoded with escape().

Note: The escape() and unescape() functions should not be used to encode or decode URIs. Use
encodeURI() and decodeURI() functions instead!
Example

In this example we use escape() to encode strings:

document.write(escape("Visit W3Schools!") + "<br />");
document.write(escape("?!=()#%&"));

</script>

Visit%20W3Schools%21
%3F%21%3D%28%29%23%25%26

JavaScript unescape() Function

The unescape() function decodes a string encoded with escape().
Syntax
unescape(string)

string Required. The string to be decoded

Tips and Notes

Note: The escape() and unescape() functions should not be used to encode or decode URIs. Use
encodeURI() and decodeURI() functions instead!
Example

In this example we first encode the strings with the escape() function, and then decode them with the
unescape() function:

var test1="Visit W3Schools!";

test1=escape(test1);
document.write (test1 + "<br />");

test1=unescape(test1);
document.write(test1 + "<br />");

</script>

Visit%20W3Schools%21
Visit W3Schools!

JavaScript eval() Function // Its important to make the code more smaller.......nice one

The eval() function evaluates a string and executes it as if it was script code.
Syntax
eval(string)

string Required. The string to be evaluated

Example

In this example we use eval() on some strings and see what it returns:

eval("x=10;y=20;document.write(x*y)");

document.write(eval("2+2"));

var x=10;
document.write(eval(x+17));

</script>

200
4
27

JavaScript String() Function

The String() function converts the value of an object to a string.
Syntax
String(object)

object Required. A JavaScript object

Tips and Notes

Note: The String() function returns the same value as toString() of the individual objects.
Example

In this example we will try to convert different objects to strings:

var test1= new Boolean(1);
var test2= new Boolean(0);
var test3= new Boolean(true);
var test4= new Boolean(false);
var test5= new Date();
var test6= new String("999 888");
var test7=12345;

document.write(String(test1)+ "<br />");

</script>

true
false

true
false
Sun Jul 12 2009 15:55:47 GMT+0530 (India Standard Time)
999 888
12345

Examples for Events ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

JavaScript onclick Event

<html>
<body>

Field1: <input type="text" id="field1" value="Hello World!">
<br />
Field2: <input type="text" id="field2">
<br /><br />
Click the button below to copy the content of Field1 to Field2.
<br />
<button onclick="document.getElementById('field2').value=
document.getElementById('field1').value">Copy Text</button>

</body>
</html>

onfocus event
<html>
<head>
function setStyle(x)
{
document.getElementById(x).style.background="yellow";
}
</script>
</head>
<body>

First name: <input type="text"
onfocus="setStyle(this.id)" id="fname">
<br />
Last name: <input type="text"
onfocus="setStyle(this.id)" id="lname">

</body>
</html>

onkeydown Event

Browser differences: Internet Explorer uses event.keyCode to retrieve the character that was
pressed and Netscape/Firefox/Opera uses event.which.

<html>
<body>
function noNumbers(e)
{

var keynum;
var keychar;
var numcheck;

if(window.event) // IE
{
keynum = e.keyCode;
}
else if(e.which) // Netscape/Firefox/Opera
{
keynum = e.which;
}
keychar = String.fromCharCode(keynum);
numcheck = /d/;
return !numcheck.test(keychar);
}
</script>

<form>
Type some text (numbers not allowed):
<input type="text" onkeydown="return noNumbers(event)" />
</form>

</body>
</html>

Date and Time Section ::::
<html>
<body>


document.write(Date());

</script>

</body>
</html>

o/p Sun Jul 12 2009 16:16:31 GMT+0530 (India Standard Time)

<html>
<body>

var minutes = 1000*60;
var hours = minutes*60;
var days = hours*24;
var years = days*365;
var d = new Date();
var t = d.getTime();
var y = t/years;
document.write("It's been: " + y + " years since 1970/01/01!");
</script>

</body>
</html>

O.p It's been: 39.554654748414514 years since 1970/01/01!

<html>
<body>


var d = new Date();
d.setFullYear(1992,10,3);
document.write(d);

</script>

</body>
</html>

O/p :Tue Nov 03 1992 16:16:32 GMT+0530 (India Standard Time)

<html>
<body>


var d = new Date();
document.write (d.toUTCString());

</script>

</body>
</html>

Sun, 12 Jul 2009 10:46:34 GMT

<html>
<body>


var d=new Date();
var weekday=new Array(7);
weekday[0]="Sunday";
weekday[1]="Monday";
weekday[2]="Tuesday";
weekday[3]="Wednesday";
weekday[4]="Thursday";
weekday[5]="Friday";
weekday[6]="Saturday";

document.write("Today it is " + weekday[d.getDay()]); // getDay function will return the number

</script>

</body>
</html>

Today is Sunday

Clock

<html>
<head>
function startTime()
{
var today=new Date();
var h=today.getHours();
var m=today.getMinutes();
var s=today.getSeconds();
// add a zero in front of numbers<10
m=checkTime(m);
s=checkTime(s);
document.getElementById('txt').innerHTML=h+":"+m+":"+s;
t=setTimeout('startTime()',500);
}

function checkTime(i)
{
if (i<10)
{
i="0" + i;
}
return i;
}
</script>
</head>

<body onload="startTime()">
<div id="txt"></div>
</body>
</html>

return current time 16:39:02

Mathematical Function :
Mathematical Methods

In addition to the mathematical constants that can be accessed from the Math object there are also
several methods available.

The following example uses the round() method of the Math object to round a number to the nearest
integer:
document.write(Math.round(4.7));

The code above will result in the following output:
5

Random method

The following example uses the random() method of the Math object to return a random number between
0 and 1:
document.write(Math.random());

The code above can result in the following output:
0.6388059778069849

The following example uses the floor() and random() methods of the Math object to return a random
number between 0 and 10:
document.write(Math.floor(Math.random()*11));

The code above can result in the following output:
4

<html>
<body>


document.write(Math.random());

</script>

</body>
</html>

<html>
<body>


document.write(Math.round(0.60) + "<br />");
document.write(Math.round(-4.40) + "<br />");
document.write(Math.round(-4.60));

</script>

</body>
</html>

The innerHTML property sets or returns the text of a link.
It will redirect u to the microsoft site
<html>
<head>
function changeLink()
{
document.getElementById('myAnchor').innerHTML="Visit W3Schools";

document.getElementById('myAnchor').href="http://www.w3schools.com";
document.getElementById('myAnchor').target="_blank";
}
</script>
</head>

<body>
<a id="myAnchor" href="http://www.microsoft.com">Visit Microsoft</a>
<input type="button" onclick="changeLink()" value="Change link">
<p>In this example we change the text and the URL of a hyperlink. We also change the target attribute.
The target attribute is by default set to "_self", which means that the link will open in the same window.
By setting the target attribute to "_blank", the link will open in a new window.</p>
</body>

</html>

Regular Expression(RegExp)

What is RegExp

RegExp, is short for regular expression.

When you search in a text, you can use a pattern to describe what you are searching for. RegExp IS this
pattern.
A simple pattern can be a single character.

A more complicated pattern consists of more characters, and can be used for parsing, format checking,
substitution and more.

You can specify where in the string to search, what type of characters to search for, and more.
Defining RegExp

The RegExp object is used to store the search pattern.

We define a RegExp object with the new keyword. The following code line defines a RegExp object called
patt1 with the pattern "e":
var patt1=new RegExp("e");

When you use this RegExp object to search in a string, you will find the letter "e".
Methods of the RegExp Object

The RegExp Object has 3 methods: test(), exec(), and compile().
test()

The test() method searches a string for a specified value. Returns true or false
Example
var patt1=new RegExp("e");

document.write(patt1.test("The best things in life are free"));

Since there is an "e" in the string, the output of the code above will be:
true

Navigator Object

Properties Description
----------------------------------------------------------------------------------------------------
appCodeName The code name of the browser.
appName The name of the browser (ie: Microsoft Internet Explorer).
appVersion Version information for the browser (ie: 4.75 [en] (Win98; U)).
appMinorVersion The minor version number of the browser.
cookieEnabled Boolean that indicates whether the browser has cookies enabled. cpuClass
The type of CPU which may be "x86"
language Returns the default language of the browser version (ie: en-US). NS
and Firefox only.
mimeTypes[] An array of all MIME types supported by the client. NS and Firefox
only.
platform[] The platform of the client's computer (ie: Win32).
plugins An array of all plug-ins currently installed on the client. NS and
Firefox only.
systemLanguage Returns the default language of the operating system (ie: en-us). IE
only.
userAgent String passed by browser as user-agent header. (ie: Mozilla/4.0
(compatible; MSIE 6.0; Windows NT 5.1))
userLanguage Returns the preferred language setting of the user (ie: en-ca). IE only.
mimeTypes An array of MIME type descriptive strings that are supported by the
browser.
onLine A boolean value of true or false.

Image Map Example
<html>
<head>
function writeText(txt)
{
document.getElementById("desc").innerHTML=txt;
}
</script>
</head>

<body>
<img src ="planets.gif" width ="145" height ="126" alt="Planets" usemap="#planetmap" />

<map name="planetmap">
<area shape ="rect" coords ="0,0,82,126"
onMouseOver="writeText('The Sun and the gas giant planets like Jupiter are by far the largest
objects in our Solar System.')"
href ="sun.htm" target ="_blank" alt="Sun" />

<area shape ="circle" coords ="90,58,3"
onMouseOver="writeText('The planet Mercury is very difficult to study from the Earth because
it is always so close to the Sun.')"
href ="mercur.htm" target ="_blank" alt="Mercury" />

<area shape ="circle" coords ="124,58,8"
onMouseOver="writeText('Until the 1960s, Venus was often considered a twin sister to the
Earth because Venus is the nearest planet to us, and because the two planets seem to share
many characteristics.')"
href ="venus.htm" target ="_blank" alt="Venus" />
</map>

<h4 id="desc"></h4>

</body>
</html>

Timing Object
<html>
<head>
function timedMsg()
{
var t=setTimeout("alert('5 seconds!')",5000);
}
</script>
</head>

<body>
<form>
<input type="button" value="Display timed alertbox!" onClick = "timedMsg()">
</form>
<p>Click on the button above. An alert box will be displayed after 5 seconds.</p>
</body>

</html>

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