JavaScript is an object-based language

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Introduction

• JavaScript is an object-based language
• Uses built-in objects
• Properties are attributes of objects
• Methods are actions performed on an object

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Introduction

• An event is the result of a users action
• Event handlers are the way to associate that
  action with the set of JavaScript codes you want
  executed

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Inserting ltSCRIPTgt Tags on a Web Page

• JavaScript code can go anywhere in HTML
• Place all JavaScript code between the ltSCRIPTgt
  and lt/SCRIPTgt tags
• Set the LANGUAGE attribute so the browser knows
  how to interpret your code
• The HTML comment line hides any script language
  the browser might not be able to interpret
• ltSCRIPT LANGUAGEJAVASCRIPTgt
• lt! Hide from old browsers

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Entering the Start ltSCRIPTgt Tag and Comment

• Click the blank line (line 10) above the lt/BODYgt
  tag

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Type ltSCRIPT LANGUAGE JAVASCRIPTgt and then
pressthe ENTER key. Type lt! Hidefrom old
browsers and thenpress the ENTER key
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Using a Flicker on a Web Page

• Changes the background color in rapid succession
• JavaScript allows you to set the background color
  multiple times, while HTML only allows you to set
  it once (in the BODY tag)

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Setting the Background Color to a Static Color

• The last color you specify will be the browsers
  final background color
• With the insertion point on line 18, type
  document.bgColorblanchedalmond and then press
  the ENTER key

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Completing the JavaScript Selection

• It is now necessary to end the comment tag and
  close the ltSCRIPTgt tag
• If necessary, click line 19. Press the ENTER key
  to create another blank line
• With the insertion point on line 20, type //-gt
  and then press the ENTER key. Type lt/SCRIPTgt and
  then press the ENTER key

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JavaScript Variables

• Used to store values temporarily
• Global variables
• Local variables
• Variables are considered global, except if they
  are declared in a user-defined function, in which
  case they are local

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JavaScript Variables
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JavaScript Variables

• JavaScript variables are loosely typed
• You are not required to define the data type
• JavaScript defines the data type for you
• String data types
• var LastName Simon
• Numeric data types
• var pageCnt 1
• Boolean data types
• var Done false

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Extracting the System Date

• Built-in Date() object
• Can be manipulated only by creating a new object
  instance
• var variable new object
• var birthDay Date(Jul, 13, 1975)
• Returns July 13, 1975 to birthDay
• var curDate new Date()
• Returns the current system date and time
  information as an object instance

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Extracting the System Date

• The variable curDate cannot be manipulated
• To extract the date, convert curDate to a string
  using the toLocaleString() and substring methods

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Extracting the System Date

• Define a new object for the date in MM/DD/YY
  HHMMSS format
• var tNow new Date()
• Extract the date and time and store it in
  MM/DD/YY HHMMSS format
• var tlocDate tNow.toLocaleString()
• Extract only the date portion from the tlocDate
  variable using relative addressing
• var tDate tlocDate.substring(0,10)

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Extracting the System Date

• Relative addressing

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Extracting the Current System Date Using the
Date() Object

• Click the Notepad button on the taskbar to
  activate the Notepad window. Click line 19 below
  the document.bgColorblanchedalmond statement

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Type var tNow new Date() and thenpress the
ENTER key. Typevar tlocDate
tNow.toLocaleString()and then press the ENTER
key. Typevar tDate tlocDate.substring(0,10)an
d then press the ENTER key
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Displaying the Current System Date

• Use plus signs () to concatenate (join) strings
  and variables

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Displaying the Current System Date in the Initial
Greeting

• Click line 22. Press the SPACEBAR four times.
  Type document.write(ltH2gtltCENTERgtWelcome, today
  is tDatelt/CENTERgtlt/H2gt) and then press the
  ENTER key

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Constructing a Message Using Several Variables

• Click line 23. Type var intro1 Hi, thanks for
  visiting our Web site, but we have moved. Please
  make a note and then press the ENTER key
• Type var intro2 of our new URL
  (www.funphonics.com) and notify the Webmaster
  about our new and then press the ENTER key

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Constructing a MessageUsing Several Variables

• Type var intro3 location. ClickltA
  Hrefhttp//www.scsite.com/gtherelt/Agt or wait 15
  seconds and then press the ENTER key
• Type var intro4 to be moved automatically to
  our new site. and then press the ENTER key

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Constructing a MessageUsing Several Variables

• Type var introMsg intro1intro2intro3intro4
  and then press the ENTER key

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Writing the Message on the Web Page

• Click line 28. Press the SPACEBAR four times.
  Type document.write(ltH4gtltFONT Colorfirebrickgt
  introMsglt/H4gtlt/FONTgt) and then press the
  ENTER key

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Calling a JavaScript Function

• Two basic methods to call a function
• Event handlers and object methods
• Code the function name in a JavaScript section at
  the logical point of execution
• setTimeout() method
• Causes a delay before an instruction is executed

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Calling a JavaScript Function
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Writing the setTimeout() Method to Execute the
chngSite() Function

• If necessary, click line 29. Press the SPACEBAR
  four times
• Type setTimeout(chngSite(), 15000) and then
  press the ENTER key

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Displaying the Last Modified Document Date

• If necessary, click line 30. Press the SPACEBAR
  four times
• Type document.write(ltBRgtltH4gtltCENTERgtThis
  document was last modified document.lastModified
  lt/CENTERgtlt/H4gt) and then press the ENTER key

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Writing a JavaScript User-Defined Function

• A function is JavaScript code written to perform
  certain tasks repeatedly
• Built-in functions

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Writing a JavaScript User-Defined Function

• User-defined functions
• Written by the Web developer
• Functions can have data passed to it
• To call a function means to have JavaScript
  execute the function

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Entering the chngSite() User-Defined Function in
the HEAD Section

• Click the blank line (line 4) between the end
  lt/TITLEgt tag and the end lt/HEADgt tag

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Type ltSCRIPT LANGUAGEJAVASCRIPTgtand then
press the ENTER key. Typelt!Hide from old
browsers and thenpress the ENTER key
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Entering the chngSite() User-Defined Function in
the HEAD Section

• Press the SPACEBAR four times. Type function
  chngSite() and then press the ENTER key. Press
  the SPACEBAR eight times. Type alert(You are
  about to be transported to the new site
  location!) and then press the ENTER key. Press
  the SPACEBAR eight times. Type location
  http//www.scsite.com/ and then press the ENTER
  key. Press the SPACEBAR four times. Type and
  then press the ENTER key. Type //-gt and then
  press the ENTER key. Type lt/SCRIPTgt and then
  press the ENTER key

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Saving the File on the Floppy Disk

• With the HTML Data Disk in drive A, click File on
  the menu bar
• Click Save on the File menu

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Testing the Web Page

• Click the Fun with Phonics button on the taskbar
• Click the Refresh button on the browser toolbar
• If you are connected to the Internet, click the
  OK button when the dialog box displays with the
  alert message
• Click the Back button on the browser toolbar to
  return to the Fun with Phonics Web page

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Printing the HTML File Using Notepad

• If necessary, click the Notepad button on the
  taskbar. Click File on the menu bar and then
  point to Print

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Click Print
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Closing Notepad and Your Browser

• Click the Close button on the browser title bar
• Click the Close button on the Notepad window
  title bar

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Summary

• Discuss how to integrate JavaScript with HTML
• Insert ltSCRIPTgt tags on a Web page
• Write start and end ltSCRIPTgt tags
• Define and use flickering to draw attention
• Describe the background color property of the
  document object

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Summary

• Set the background color of a Web page using
  JavaScript
• Save the HTML file
• Test the Web page
• Discuss JavaScript variables
• Extract the system date
• Use several variables to construct a message

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Summary

• Describe the write() method of the document
  object
• Write a user-defined function that displays a
  message and links visitors to a new Web site
• Describe how the setTimeout() method works
• Use the lastModified property to display the last
  modified document date
• Print an HTML Notepad file

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What You Should Know
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Project 8 Complete