Javascript1

Making dynamic pages with
javascript

Lecture 1

Java script
 java versus javascript
Javascript is a scripting language that will
allow you to add real programming to your
webpages.
Its not stand alone language as java.

uses for javascript
 Browser Detection
Detecting the browser used by a visitor at your page. Depending on the
browser, another page specifically designed for that browser can then
be loaded.
 Cookies
Storing information on the visitor's computer, then retrieving this
information automatically next time the user visits your page. This
technique is called "cookies".
 Control Browsers
Opening pages in customized windows, where you specify if the
browser's buttons, menu line, status line or whatever should be present.

 Validate Forms
Validating inputs to fields before submitting a form.
An example would be validating the entered email address to see if it
has an @ in it, since if not, it's not a valid address.

Position of script tag
1. Internal
 Between the head tag / body tag
 What is the different between the scripting between head tag and
between body tag?
 In the tag itself
 example <p onclick=“ alert(‘good’)”> text </p>

2. External
<HTML> One
<Head> quote
<SCRIPT LANGUAGE="JavaScript" src=“jfile.js"></SCRIPT>
</Head>
<Body>

</Body>
</HTML>

Components of javascript
1. <script> tag
2. Objects
( window, document, form)
1. Properties
document.color
1. Methods
document.write( )
document.write( string)
1. Variables
var name=“ ali”
var age=30
1. Operators and expression
 + ,- , % ,/ …..

.Cont
6. Statements
 If - If … else
 For
 while
7. Event handlers.
 KB events: onkeydown – onkeyup- onkeypress
 Mouse events : onmousemove – onmouseover-
onmousedown- onmouseout- onmouseup- onclick-
ondblclick
 Load & unload
 Its specified in the <body> tag.
 <body onload=“……”>

Script tag
 <SCRIPT LANGUAGE="JavaScript">
 code
</SCRIPT>
Notes:
 Its necessary to but the code between
comment tag. Why?
 Case sensitive write (ex. document.Write <> document.write)
 Comment statement (// or /* */)

output methods
1. alert
2. Write
3. Print

alert
 alert (“ text”) = window.alert(“ text”)
 Ex.
 In the tag :<TagName event=”code statement"></TagName>

 Example : <p onclick= “ alert(‘ click is occurred’) “ > click </p>

 Using script tag in the head
<head>
<SCRIPT LANGUAGE="JavaScript">
Function
 function
</SCRIPT> when event
</head> is occurred
Calling:
<p onclick=“ demo( ) “ > click </p>

Write method
 Examples:
 documet.write(“hello”)
 document.write("<font color=ff0000>
red text </font>”)
 document.write("<font color=ff0000>
red text </font> <br> <font
color=00ff00> green text </font>”)

 Notes:
 Use tags within document

( )Newline in write( ) and alert

document.write(" ppu <br> graphics")
 alert(" are you sure n press OK" )

Input methods
1. Confirm
2. Prompt

 confirm
 One of window methods as alert. It return value false/true by
contrast of alert.
 confirm(“ message ");
or
window.confirm(“ message");

 to show the result:
Alert( confirm (message) )

prompt
 Window method that pass a message to user
(undefined is default value)
 Prompt( “message”, ”default value”)

 Alert(prompt(…….))

variables
 Types of variables:
 String
 Numbers
 Boolean
 Null
 Naming variables
 Ex these variable names are correct
 Address1
 A4xb5
 lastName
 _firstName
 parent_Name
 Not correct
 1stName
 ?subName
 last name
 @ userID

Declaration/assignment
 var firstName;
 var firstName, lastName, userID;
 var firstName, lastName = “ali", userID = 13;

 assignment
 var stname;
 stname = "Ahmed“;

cont.

<script>
function demo( )
{
var username = ”ali";
alert("welcomen"+username);
}
</script>

- improve this code in order to accept your name from
the KB.

Conditional statement
 If (condition) {…..}
 If (condition)
{……}
Else
{ ……}
 If (condition)
{……}
Else if ( )
{ ……}

example
<HEAD>
<SCRIPT LANGUAGE="JavaScript">

</SCRIPT>
</HEAD>

switch
switch(value/expression) {
case " val1" :

break;
case " val2 " :

break;
case " val3 " :
break;
.
.
default :

example
var num = 4;
switch( num )
{ case 1 :
alert( " num is n one " );
break;
case 2 :
alert( " num is n two " );
break;
case 3 :
alert( ” num is n three " );
break;
default :
alert( " num is " + num );
break;
}

Iteration
 For
 While

 Print your name four times, each one in a
separate line.
var x = 0;
for( i=1; i<5 ; i++ )
{
document.write( “ali” <br> )
}

while
1- var i = 0;
while( i<5 )
{
document.write( “ali” + "<br>" );
i++;
}
2-
var userPassword = "123";
var password = prompt(“enter password", “password ");
while( password != userPassword )
{
alert( “ wrong try again " );
password = prompt(“enter password", “password ");
}
Alert (“its correct”);

Good site
 http://www.jsmadeeasy.com/javascripts/Pull%20Down%20Su
 http://www.yourhtmlsource.com/javascript/
 http://www.webteacher.com/javascript/ch01.html

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