The JavaScript Programming Language

1
Introduction

• The JavaScript Programming Language
• Applets
• The Java Programming Language
• Web Page Counters

2
The JavaScript Programming Language

• Introduction
• JavaScript and HTML
• Event Handlers
• Sample JavaScript Code

3
The JavaScript Programming Language
Introduction

• Client-side Scripting language
• Not Java
• Statements usually embedded in HTML code
• Simple, interpreted programming language

4
The JavaScript Programming Language
Introduction

• Common uses
• Alert boxes
• Color fades
• Dynamically converts form elements
• Information in status line
• Verify form input

5
The JavaScript Programming Language
JavaScript and HTML

• ltSCRIPTgtlt/SCRIPTgt
• LANGUAGEJavaScript
• SRC
• program.js

6
The JavaScript Programming Language
JavaScript and HTML

• ltSCRIPT LANGUAGE JavaScriptgt
• lt!- - Begin hiding for browsers that cannot
  process JavaScript.
• Include JavaScript statements here.
• Last JavaScript statement goes here.
• End hiding script. - -gt
• lt/SCRIPTgt

7
JavaScript and HTML
ltHtmlgtltHeadgtltTitlegtonLoad Examplelt/Titlegt ltScript
Language JavaScriptgt lt!- - Begin hiding for
browsers that cannot support script. function
ready() document.forms0.elements0.valueLet
s go! //Stop hiding script. --gt lt/Scriptgt lt/Hea
dgt ltBody onLoad ready()gt ltFormgt ltInput Type
text Value Loadinggt lt/Formgtlt/Bodygtlt/Htmlgt
8
The JavaScript Programming Language
Event Handlers

• onMouseOver and onMouseOut
• onMouseOver
• When you move mouse over item, action triggered
• onMouseOut
• When you move mouse out of area, action triggered

9
The JavaScript Programming Language
Event Handlers

• onMouseOver and onMouseOut
• ltA HREF ASSIGNMENTS/assign.html
• onMouseOver document.images0.srcGRAPHICS/4
  ON.GIF
• window.status Assignments
• onMouseOut document.images0.srcGRAPHICS/4
  OFF.GIF
• window.status gt
• ltIMG SRC GRAPHICS/4OFF.GIF
• WIDTH 42 HEIGHT 42 ALT
  Assignments
• BORDER 0gt
• lt/Agt

10
The JavaScript Programming Language
Event Handlers

• When user mouses over image
• Loads a new image
• Assignments displayed in status line

11
The JavaScript Programming Language
Event Handlers
onClick and alert   ltA HREF killface.html
onClick alert(Thanks for loading
my pageKillface.)gt Killfaces Page lt/Agt
12
The JavaScript Programming Language
Event Handlers
13
Event Handlers
onChange and confirm ltHtmlgtltHeadgtltTitlegtConfirm
Boxlt/Titlegt ltScript Language JavaScriptgt funct
ion question(name) var theAnswer
confirm(Are you really name
?) lt/Scriptgtlt/Headgt ltBodygtltFormgt ltInput Type
text Value Enter your name
onChange question(value)gt lt/Formgtlt/Bodygtlt/Html
gt
14
The JavaScript Programming Language
Sample JavaScript Code

• ltFORMgt
•  
• ltSTRONGgt
• Temperature Conversion Example Using JavaScript
  ltBRgt
• lt/STRONGgt
•  
• ltPgt nbsp lt/Pgt
•  

15
The JavaScript Programming Language
Sample JavaScript Code

• ltINPUT TYPE text
• NAME cels
• VALUE 0
• SIZE 3
• MAXLENGTH 3
• onChange fahr.value 1.8 value 32gt
• 176 ltSTRONGgtClt/STRONGgt
• nbsp ltSTRONGgtequalslt/STRONGgt nbsp
•  

16
The JavaScript Programming Language
Sample JavaScript Code

• ltINPUT TYPE text
• NAME fahr
• VALUE 32
• SIZE 3
• MAXLENGTH 3
• onChange cels.value (value - 32)/1.8gt
• 176 ltSTRONGgtFlt/STRONGgt 
• lt/FORMgt

17
The JavaScript Programming Language
Sample JavaScript Code

• NAME fahr
• fahr.value

18
Applets

• Introduction
• HTML Applet Tags
• Java-Enabled Browsers
• Sample Applets

19
Applets
Introduction

• Little application
• Primary features
• Information is dynamic
• Can respond to input
• Program downloaded from Web server
• Runs on the client

20
Applets
HTML Applet Tags

• ltAPPLETgtlt/APPLETgt
• Attributes
• ALIGN ALT
• CODE CODEBASE
• HEIGHT HSPACE
• NAME VSPACE
• WIDTH

21
Applets
Java-Enabled Browsers

• Browsers that are text-only or not Java-enabled
  ignore applet tags
• Display messages

22
Applets
Sample Applets

• ltAPPLET CODE HiMom.class
• HEIGHT 75
• WIDTH 125gt
• ltPARAM NAME message
• VALUE Hi Mom. How do you like my
  applet?gt
• lt/APPLETgt

23
Applets
Sample Applets
24
The Java Programming Language

• Introduction
• Java and Object-Oriented Programming

25
The Java Programming Language
Introduction

• Sun Microsystems, 1995
• Java Virtual Machine

26
The Java Programming Language
Java and Object-Oriented Programming

• Java supports object-oriented programming (OOP)
• Object, Class
• Inheritance

27
Web Page Counters

• HTML Code for a Counter
• Counter Usefulness
• Counter Display Decision

28
Web Page Counters
HTML Code for a Counter

• Absolute URL for CGI script as value of SRC
  attribute of image tag
• Parameters passed using get METHOD

ltIMG SRC http//www.website-hit-counters.com/c
gi-bin/image.pl?URL51939-4076 ALT free
website hit countergt
29
Web Page Counters
Counter Usefulness

• Number of hits per page
• Advertising rates
• Advertising for the counter company

Counter Display Decision
Some users offended by counters