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JAVA Script

JavaScript is a scripting language

JavaScript was designed to add interactivity to HTMLpages

A scripting language is a lightweight programming

language JavaScript is usually embedded directly into HTML

pages

JavaScript is an interpreted language (means that scripts

execute without preliminary compilation) Everyone can use JavaScript without purchasing a

license

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JavaScript's official name is ECMAScript.

ECMAScript is developed and maintained by the ECMAorganization.

ECMA-262 is the official JavaScript standard.

The language was invented by Brendan Eich at Netscape (withNavigator 2.0), and has appeared in all Netscape and Microsoft

browsers since 1996.

The development of ECMA-262 started in 1996, and the firstedition of was adopted by the ECMA General Assembly in June1997.

The standard was approved as an international ISO (ISO/IEC16262) standard in 1998.

The development of the standard is still in progress.

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JS can do.

JavaScript gives HTML designers a

programming tool

JavaScript can put dynamic text into an HTML

page JavaScript can read and write HTML elements

JavaScript can be used to validate data

JavaScript can be used to detect the visitor'sbrowser

JavaScript can be used to create cookies

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Syntax:

...

Eg:

document.write(Welcome to IIST!");

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Where JS can be?

Scripts in Scripts to be executed when they are called, or

when an event is triggered, go in the head section.

Scripts in

Scripts to be executed when the page loads go in

the body section.

Scripts in and

You can place an unlimited number of scripts inyour document, so you can have scripts in both the

body and the head section.

External JavaScript

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JavaScript Statements

A JavaScript statement is a command to a

browser.

JavaScript is Case Sensitive JavaScript Code - is a sequence of

JavaScript statements.

JavaScript Blocks - statements can begrouped together in blocks.

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JavaScript Comments

// Single line comment

/* Multi - line comment */

Comments at the end of the line //

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JavaScript Variables

Variable names are case sensitive (a and

A are two different variables)

Variable names must begin with a letter or

the underscore character

Syntax:

var x;

x=5;

x=IIST;

var x=10;Note: Variable can be assigned without declaration.

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JavaScript OperatorsArithmetic Operators

+ , - , * , / , % , ++ , --Assignment Operators

= , += , -= , *= , /= , %= ,.=

Comparison Operators== , != , > , < , =

Logical Operators

&& , || , !Conditional Operator

variablename=(condition)?value1:value2

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The + Operator Used on Strings

str1="What a very";

str2="nice day";

str3=str1+str2;

Adding Strings and Numbers

x=5+5;

x="5"+"5";

x=5+"5";

x="5"+5;

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Control Statements

(i) if statement

if (condition)

code to be executed if condition is true;

(ii) if...else statementif (condition)

code to be executed if condition is true;

elsecode to be executed if condition is false;

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(iii) If...else if....else statement

if (condition)

code to be executed if condition is true;

else if (condition)

code to be executed if condition is true;

else if (condition)

code to be executed if condition is true;

elsecode to be executed if condition is false;

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(iv) Switch statement

switch (n)

{case label1:

code to be executed if n=label1;

break;

case label2:code to be executed if n=label2;

break;

default:

code to be executed if n is differentfrom both label1 and label2;

}

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Loops

(i) while loop

while (condition){

code to be executed;

}(ii) do While loop

do

{code to be executed;

}while (condition);

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(iii) for loop

for (init; condition; increment)

{code to be executed;

}

(iv) break and continue Statements

break will terminate the loop

continue will break the loop for thatiteration and continue with the nextvalue

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(v) for - in Statement

for (variable in object){

code to be executed

}

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JS Function

Syntax:

function functionname(var1,var2,...,varX)

{some code

}

Function call:functionname(var1,var2,,varX);