09 javascript

8/7/2019 09 Javascript

1/22

assan an


2/22

JavaScript

JavaScript is thescripting language of the

Web.

JavaScript is used in millions of Web pages

to add functionality, validate forms, detectbrowsers, and much more.

8/9/2010 2Hassan Khan


3/22

What is JavaScript?

JavaScript was designed to add interactivity to HTML

JavaScript is a scripting language

A scripting language is a lightweight programminglanguage

JavaScript is usually embedded directly into HTMLpages

ava cr p s an n erpre e anguage means a

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

license



4/22

Example

document.write("This is my first JavaScript!");



5/22

How to Handle Simple

Browsers

Browsers that do not support JavaScript, will display

.

The HTML comment tag should be used to "hide" the

JavaScript.

Just add an HTML comment ta (end of comment) afterthe last JavaScript statement.



6/22

Example

the JavaScript comment symbol. This preventsJavaScript from executing the --> tag.



7/22

What can a JavaScript do?

JavaScript gives HTML designers a programming

oo

JavaScript can put dynamic text into an HTML pageJavaScript can react to events

JavaScript can read and write HTML elements

JavaScript can be used to validate data

ava cr p can e use o e ec e v s or s

browser JavaScript can be used to create cookies



8/22

How To Use?

tag is used to insert a JavaScript into

an HTML page.

Between tag

e ween < ea > ag



9/22

How To Use (Cont.)?

JavaScripts in the body section will be

executed WHILE the page loads.

JavaScripts in the head section will be.



10/22

JavaScript Statements

JavaScript is case sensitive.

Use of semicolon(;) in the end of statement isoptional.

document.write("Hello");

document.write("Hello")



11/22

JavaScript Comments

Single line comments start with //.

Multi line comments start with /* and end with.



12/22

JavaScript Variables JavaScript variables are used to hold values

x=5, y=6, z=x+y

Rules for JavaScript variable names:

Variable names are case sensitive (y and Y

are two different variables)

Variable names must begin with a letter orthe underscore character



13/22

JavaScript Variables

Declaration

var x;var carname;

Assign Values

x= ;

carname=Toyota";



14/22

JavaScript Arithmetic Operators

Y=5



15/22

JavaScript Assignment Operators

x = 5 and y=10



16/22

+ Operator and Strings

To add two or more string variables together,

use the + operator.



17/22

Comparison Operators



18/22

Logical Operators



19/22

If...Else Statements

used to perform different actions based on different

. if statement - use this statement to execute some

code only if a specified condition is true

if...else statement - use this statement to executesome code if the condition is true and another codeif the condition is false

...e se ....e se s a emen - use s s a emen o

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



20/22

Example (If)



21/22

Example (If...else)



22/22

Example(If...else if...else)


09 javascript

Documents