The document provides information about various components of the internet and web including the World Wide Web, hyperlinks, TCP/IP protocol, URLs, HTTP, IP addresses, HTML, tags, parsing, JavaScript, client-side and server-side JavaScript, bugs, debugging, adding JavaScript to web pages, comments, and variables. It includes definitions and brief explanations of these terms.

1. 11
Internet 213Internet 213

2. 2
World Wide WebWorld Wide Web
 Also called as WWW or W3Also called as WWW or W3
 Allows users to use the InternetAllows users to use the Internet
easilyeasily
 The web lets you connect by simplyThe web lets you connect by simply
clicking theclicking the hyperlinkhyperlink..
 It applies a protocol calledIt applies a protocol called TCP/IPTCP/IP

3. 3
HyperlinkHyperlink
 This is a word, phraseThis is a word, phrase
or graphic image thator graphic image that
have URL’s (webhave URL’s (web
address) hidden onaddress) hidden on
them. Usually anthem. Usually an
underlined word orunderlined word or
phrase.phrase.

4. 4
Transmission Control Protocol /Transmission Control Protocol /
Internet Protocol (TCP/IP)Internet Protocol (TCP/IP)
 The protocol of the InternetThe protocol of the Internet
 Let the computers communicateLet the computers communicate
Note: Internet itself is a massiveNote: Internet itself is a massive
network of hardware and softwarenetwork of hardware and software
while Web is the application facilitieswhile Web is the application facilities
provided by the Internetprovided by the Internet

5. 5
Uniform Resource LocatorUniform Resource Locator
 A unique address for a webA unique address for a web
page or documentpage or document
 It consists of protocol andIt consists of protocol and
domain name or IP address anddomain name or IP address and
a file namea file name

6. 6
http://www.yahoo.comhttp://www.yahoo.com
Protocol or
Scheme Host
Domain
Top-level
domain or
type of site

7. 7
HyperText Transfer ProtocolHyperText Transfer Protocol
 Manages the hypertext links that areManages the hypertext links that are
used to navigate the Webused to navigate the Web
 You can think of HTTP as drivingYou can think of HTTP as driving
the Webthe Web
 Ensures that browser correctlyEnsures that browser correctly
process and display the various typesprocess and display the various types
of information contained in Webof information contained in Web
pagespages

8. 8
IP AddressIP Address
 Another way to uniquely identifyAnother way to uniquely identify
computers or devices connectedcomputers or devices connected
to the Internetto the Internet
 Using a series of four groups ofUsing a series of four groups of
numbers separated by periodsnumbers separated by periods

9. 9
HyperText MarkupHyperText Markup
LanguageLanguage
 The lingua franca of the Web.The lingua franca of the Web.
 It is used to create web pages.It is used to create web pages.

10. 10
TagsTags
 Formatting instructions that isFormatting instructions that is
used by HTML documentsused by HTML documents
 That’s why it is called MarkupThat’s why it is called Markup
because of using of tags inbecause of using of tags in
defining elements of the Webdefining elements of the Web

11. 11
Parsing or RenderingParsing or Rendering
 The process of assembling andThe process of assembling and
formatting an HTML documentformatting an HTML document
of a web browserof a web browser

12. 12
Brief history of JSBrief history of JS
 JavaScriptJavaScript, originally nicknamed, originally nicknamed
LiveWireLiveWire and thenand then LiveScriptLiveScript
when it was created bywhen it was created by NetscapeNetscape,,
should in fact be calledshould in fact be called
ECMAscriptECMAscript as it was renamedas it was renamed
when Netscape passed it to thewhen Netscape passed it to the
ECMA for standardisation.ECMA for standardisation.

13. 13
Role of JS on the WebRole of JS on the Web
 Brings HTML to life andBrings HTML to life and
makes Web pages dynamic.makes Web pages dynamic.

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JavaScriptJavaScript
 It is a scripting language (refers toIt is a scripting language (refers to
programming languages that areprogramming languages that are
executed by an interpreter fromexecuted by an interpreter from
within a Web browser)within a Web browser)

15. 1515
Formats of JavaScriptFormats of JavaScript

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Client-side JavaScriptClient-side JavaScript
 Programs are passed to thePrograms are passed to the
computer that the browser is on,computer that the browser is on,
and that computer runs them.and that computer runs them.

17. 17
Server-Side JavaScriptServer-Side JavaScript
 The alternative is server side,The alternative is server side,
where the program is run on thewhere the program is run on the
server and only the results areserver and only the results are
passed to the computer that thepassed to the computer that the
browser is on. Examples of thisbrowser is on. Examples of this
would be PHP, Perl, ASP, JSP etcwould be PHP, Perl, ASP, JSP etc

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Logic and DebuggingLogic and Debugging

19. 19
BugBug
 Any error in a program thatAny error in a program that
causes it to function incorrectly,causes it to function incorrectly,
whether due to incorrect syntax orwhether due to incorrect syntax or
flaws in logicflaws in logic

20. 20
DebuggingDebugging
 Describes the act of tracing andDescribes the act of tracing and
resolving errors in a program.resolving errors in a program.
 First coined by Grace MurrayFirst coined by Grace Murray
HopperHopper

21. 2121
A FirstA First
JavaScriptJavaScript
ProgramProgram

22. 22
The <Script> TagThe <Script> Tag
 It is used to notify the WebIt is used to notify the Web
Browser that the commands thatBrowser that the commands that
follow it need to be interpreted byfollow it need to be interpreted by
a scripting engine.a scripting engine.

23. 23
LanguageLanguage
 Attribute of the <script> tag tellsAttribute of the <script> tag tells
the browser which scriptingthe browser which scripting
language and which version of thelanguage and which version of the
scripting language is being used.scripting language is being used.

24. 24
Note:Note:
 If you omit the Language attributeIf you omit the Language attribute
from the <script> tag, yourfrom the <script> tag, your
JavaScript program should still run.JavaScript program should still run.
 However, the Internet is alwaysHowever, the Internet is always
changing, it is difficult to determinechanging, it is difficult to determine
whether competing scriptingwhether competing scripting
languages such as VBScript willlanguages such as VBScript will
become dominantbecome dominant

25. 25
Creating a JavaScript ProgramCreating a JavaScript Program
1. To start a JavaScript program1. To start a JavaScript program
use the <script> taguse the <script> tag
<Script language=“JavaScript”> -<Script language=“JavaScript”> -
specifying your browser that yourspecifying your browser that your
using JavaScriptusing JavaScript
2. Close it using </script>2. Close it using </script>

26. 26
3. Use the comment tag to tell the3. Use the comment tag to tell the
incompatible browser to ignoreincompatible browser to ignore
the code that follows.the code that follows.
<!-- your codes here --><!-- your codes here -->
4. You can embed JavaScript on4. You can embed JavaScript on
head or body depending on thehead or body depending on the
application of your scriptapplication of your script

27. 27
My First JavaScript ProgramMy First JavaScript Program
Hello WorldHello World

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JavaScript is an OOPJavaScript is an OOP
 Object-Oriented ProgrammingObject-Oriented Programming
(OOP), in computer science, type of(OOP), in computer science, type of
high-level computer language thathigh-level computer language that
uses self-contained, modularuses self-contained, modular
instruction sets for defining andinstruction sets for defining and
manipulating aspects of a computermanipulating aspects of a computer
program.program.

29. 29
ObjectObject
 A programming code and dataA programming code and data
that can be treated as anthat can be treated as an
individual unit or componentindividual unit or component
 Ex. Document objectEx. Document object

30. 30
StatementsStatements
 Individual lines in a programmingIndividual lines in a programming
languagelanguage

31. 31
MethodsMethods
 Group related statementsGroup related statements
associated with an objectassociated with an object
 Ex. write( ) and writeln( )Ex. write( ) and writeln( )

32. 32
Document ObjectDocument Object
 Represents the content of aRepresents the content of a
browser’s windowbrowser’s window
 Any text, graphics, or otherAny text, graphics, or other
information displayed in a webinformation displayed in a web
page is part of the documentpage is part of the document
objectobject

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ArgumentArgument
 Any type of information that canAny type of information that can
be passed to a methodbe passed to a method
 Ex. The text string within theEx. The text string within the
write() and writeln methods of thewrite() and writeln methods of the
Document objectDocument object

34. 34
Text or Literal StringText or Literal String
 Text that is contained withinText that is contained within
double quotation marks.double quotation marks.
 Ex. <“this is a ‘text’ string”>Ex. <“this is a ‘text’ string”>
 Output: this is a ‘text’ stringOutput: this is a ‘text’ string

35. 35
Note:Note:
 The only difference between theThe only difference between the
write() and writeln() methods is thatwrite() and writeln() methods is that
the writeln method adds a carriagethe writeln method adds a carriage
return after the line of text.return after the line of text.
 However it will be only recognized ifHowever it will be only recognized if
it is within the HTML <PRE> tagit is within the HTML <PRE> tag
pair.pair.

36. 36
<PRE> Tag<PRE> Tag
 Short for Preformatted TextShort for Preformatted Text
 Tells a Web browser that any textTells a Web browser that any text
and line breaks contained betweenand line breaks contained between
opening and closing tag are to beopening and closing tag are to be
rendered exactly as they appearrendered exactly as they appear
 Known as Container ElementKnown as Container Element
because it contains text and otherbecause it contains text and other
HTML tagsHTML tags

37. 37
JavaScript is Case SensitiveJavaScript is Case Sensitive
 Document.write is not similar toDocument.write is not similar to
document.writedocument.write
 Uppercase D will not be recognizedUppercase D will not be recognized
as an object and will cause erroras an object and will cause error
 You must use lowercase d whenYou must use lowercase d when
referring to document objectreferring to document object

38. 38
JavaScript VariablesJavaScript Variables
 Then name must start with anThen name must start with an
alphabetic (a-z or A-Z) character oralphabetic (a-z or A-Z) character or
an underscore (_)an underscore (_)
 The rest of the name can contain anyThe rest of the name can contain any
letter, any digit, or an underscore.letter, any digit, or an underscore.
 Can’t contain a spaceCan’t contain a space
 Avoid JavaScript reserved words asAvoid JavaScript reserved words as
the names of variablesthe names of variables

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Debugging a ScriptDebugging a Script

40. 40
1. Capitalization1. Capitalization
 JavaScript is a case sensitiveJavaScript is a case sensitive
language, meaning that it treatslanguage, meaning that it treats
capital and lowercase versions ofcapital and lowercase versions of
the same letter as differentthe same letter as different
charactercharacter

41. 41
2. Spacing2. Spacing
 Some parts of a script canSome parts of a script can
encounter error if incorrectencounter error if incorrect
spacing is used.spacing is used.
 The best way to avoid spacingThe best way to avoid spacing
error is to pay careful attention toerror is to pay careful attention to
spacing while you enter codespacing while you enter code

42. 42
3. Parenthesis( ), Brackets3. Parenthesis( ), Brackets
[ ], Braces{ } & Quotes “”[ ], Braces{ } & Quotes “”
 JavaScript often uses four typesJavaScript often uses four types
of symbols to enclose arguments,of symbols to enclose arguments,
values or numbers.values or numbers.

43. 43
4. Typographical Errors4. Typographical Errors
 Error in entering command suchError in entering command such
as zero (0) to the letter (O).as zero (0) to the letter (O).

44. 44
5. Others5. Others
 JavaScript-compatible browserJavaScript-compatible browser
often display a JavaScript erroroften display a JavaScript error
window describes the type ofwindow describes the type of
error the browser encountered.error the browser encountered.

45. 4545
AddingAdding
JavaScript to aJavaScript to a
PagePage

46. 46
Body SectionBody Section
<body><body>
<script Language="Javascript"><script Language="Javascript">
<!--<!--
document.writeln("Hello World");document.writeln("Hello World");
-->-->
</script></script>
</body></body>

47. 47
Head SectionHead Section
<head><head>
<script Language="Javascript"><script Language="Javascript">
<!--<!--
document.writeln("Hello World");document.writeln("Hello World");
-->-->
</script></script>
</head></head>

48. 48
JavaScript Source FileJavaScript Source File
 A JavaScript code in an externalA JavaScript code in an external
filefile
 Designated with the file extensionDesignated with the file extension
of js and contains only JavaScriptof js and contains only JavaScript
statementsstatements

49. 49
Reasons Behind .js Source FileReasons Behind .js Source File
 Your HTML document will be neaterYour HTML document will be neater
 The JavaScript code can be sharedThe JavaScript code can be shared
among multiple HTML documentsamong multiple HTML documents
 JavaScript Source Files hideJavaScript Source Files hide
JavaScript code from incompatibleJavaScript code from incompatible
browsersbrowsers
 JavaScript source files help hide yourJavaScript source files help hide your
JavaScript codeJavaScript code

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Adding CommentsAdding Comments
To a JavaScriptTo a JavaScript
ProgramProgram

51. 51
CommentComment
 Nonprinting lines that you placeNonprinting lines that you place
in your code to contain variousin your code to contain various
types of remarks, including nametypes of remarks, including name
of the program, your name andof the program, your name and
the date you created and etc.,the date you created and etc.,

52. 52
Double Slash (//)Double Slash (//)
 Indicates a single lineIndicates a single line
comment. Everything after itcomment. Everything after it
on the same line will beon the same line will be
ignored by the script engine.ignored by the script engine.

53. 53
Slash-Asterisk (/* & */)Slash-Asterisk (/* & */)
 Indicates a block comment.Indicates a block comment.
Everything after it will beEverything after it will be
ignored by the script engineignored by the script engine
until an asterisk-slash isuntil an asterisk-slash is
encountered.encountered.