JavaScript Objects

IPA
1st
Semester, 2007-2008
Internet 1
Ch. 13
JavaScript: Objects
attasr@ipa.edu.sa

09/30/15 © Reem Al-Attas 2
Introduction
Use JavaScript to manipulate every
element of XHTML document from a script
Reference for several of JavaScript’s built-
in objects
Demonstrates the capabilities

Thinking About Objects
Objects
 Attributes
 Behaviors
 Encapsulate data and methods
 Property of information hiding
 Details hidden within the objects themselves

Math Object
Allow the programmer to perform many
common mathematical calculations

Math Object
Method Description Example
abs( x ) absolute value of x abs( 7.2 ) is 7.2
abs( 0.0 ) is 0.0
abs( -5.6 ) is 5.6
ceil( x ) rounds x to the smallest
integer not less than x
ceil( 9.2 ) is 10.0
ceil( -9.8 ) is -9.0
cos( x ) trigonometric cosine of x
(x in radians)
cos( 0.0 ) is 1.0
exp( x ) exponential method ex exp( 1.0 ) is 2.71828
exp( 2.0 ) is 7.38906
floor( x ) rounds x to the largest
integer not greater than x
floor( 9.2 ) is 9.0
floor( -9.8 ) is -10.0
log( x ) natural logarithm of x
(base e)
log( 2.718282 ) is 1.0
log( 7.389056 ) is 2.0
max( x, y ) larger value of x and y max( 2.3, 12.7 ) is 12.7
max( -2.3, -12.7 ) is -2.3Fig. 12.1 Math object methods.

Math Object
min( x, y ) smaller value of x
and y
min( 2.3, 12.7 ) is 2.3
min( -2.3, -12.7 ) is -12.7
pow( x, y ) x raised to power y
(xy)
pow( 2.0, 7.0 ) is 128.0
pow( 9.0, .5 ) is 3.0
round( x ) rounds x to the
closest integer
round( 9.75 ) is 10
round( 9.25 ) is 9
sin( x ) trigonometric sine of
x (x in radians)
sin( 0.0 ) is 0.0
sqrt( x ) square root of x sqrt( 900.0 ) is 30.0
sqrt( 9.0 ) is 3.0
tan( x ) trigonometric tangent
of x
(x in radians)
tan( 0.0 ) is 0.0
Fig. 12.1 Math object methods.

Math Object
Constant Description Value
Math.E Base of a natural
logarithm (e).
Approximately 2.718.
Math.LN2 Natural logarithm of 2. Approximately 0.693.
Math.LN10 Natural logarithm of 10. Approximately 2.302.
Math.LOG2E Base 2 logarithm of e. Approximately 1.442.
Math.LOG10E Base 10 logarithm of e. Approximately 0.434.
Math.PI π—the ratio of a circle’s
circumference to its
diameter.
Approximately
3.141592653589793.
Math.SQRT1_2 Square root of 0.5. Approximately 0.707.
Math.SQRT2 Square root of 2.0. Approximately 1.414.
Fig. 12.2 Properties of the Math object.

String Object
JavaScript’s string and character-
processing capabilities
Appropriate for processing names,
addresses, credit card information, etc.

Fundamentals of Characters and
Strings
Characters
 Fundamental building blocks of JavaScript
programs
String
 Series of characters treated as a single unit

12.4.2 Methods of the String
ObjectMethod Description
charAt( index ) Returns a string containing the character at the specified index. If there is no
character at the index, charAt returns an empty string. The first character is
located at index 0.
charCodeAt( index ) Returns the Unicode value of the character at the specified index. If there is
no character at the index, charCodeAt returns NaN (Not a Number).
concat( string ) Concatenates its argument to the end of the string that invokes the method.
The string invoking this method is not modified; instead a new String is
returned. This method is the same as adding two strings with the string
concatenation operator + (e.g., s1.concat( s2 ) is the same as s1 +
s2).
fromCharCode(
value1, value2, )
Converts a list of Unicode values into a string containing the corresponding
characters.
indexOf(
substring, index )
Searches for the first occurrence of substring starting from position index in
the string that invokes the method. The method returns the starting index of
substring in the source string or –1 if substring is not found. If the index
argument is not provided, the method begins searching from index 0 in the
source string.
lastIndexOf(
substring, index )
Searches for the last occurrence of substring starting from position index and
searching toward the beginning of the string that invokes the method. The
method returns the starting index of substring in the source string or –1 if
substring is not found. If the index argument is not provided, the method
begins searching from the end of the source string.
Fig. 12.3 String object methods.

Methods of the String Object
slice( start, end ) Returns a string containing the portion of the string from index start
through index end. If the end index is not specified, the method returns a
string from the start index to the end of the source string. A negative end
index specifies an offset from the end of the string starting from a
position one past the end of the last character (so –1 indicates the last
character position in the string).
split( string ) Splits the source string into an array of strings (tokens) where its string
argument specifies the delimiter (i.e., the characters that indicate the end
of each token in the source string).
substr(
start, length )
Returns a string containing length characters starting from index start in
the source string. If length is not specified, a string containing characters
from start to the end of the source string is returned.
substring(
start, end )
Returns a string containing the characters from index start up to but not
including index end in the source string.
toLowerCase() Returns a string in which all uppercase letters are converted to lowercase
letters. Non-letter characters are not changed.
toUpperCase() Returns a string in which all lowercase letters are converted to uppercase
letters. Non-letter characters are not changed.
toString() Returns the same string as the source string.
valueOf() Returns the same string as the source string.

Methods of the String Object
Methods that generate
XHTML tags
anchor( name ) Wraps the source string in an anchor element
(<a></a>) with name as the anchor name.
blink() Wraps the source string in a <blink></blink>
element.
fixed() Wraps the source string in a <tt></tt>
element.
link( url ) Wraps the source string in an anchor element
(<a></a>) with url as the hyperlink location.
strike() Wraps the source string in a
<strike></strike> element.
sub() Wraps the source string in a <sub></sub>
element.
sup() Wraps the source string in a <sup></sup>
element.

Character Processing Methods
 charAt
 Returns the character at specific position
 charCodeAt
 Returns Unicode value of the character at specific
position
 fromCharCode
 Returns string created from series of Unicode values
 toLowerCase
 Returns lowercase version of string
 toUpperCase
 Returns uppercase version of string

1 <?xml version = "1.0"?>
2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
3 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
4
5 
6 
7
8 <html xmlns = "http://www.w3.org/1999/xhtml">
9 <head>
10 <title>Character Processing Methods</title>
11
12 <script type = "text/javascript">
13 <!--
14 var s = "ZEBRA";
15 var s2 = "AbCdEfG";
16
17 document.writeln( "<p>Character at index 0 in '" +
18 s + "' is " + s.charAt( 0 ) );
19 document.writeln( "<br />Character code at index 0 in '"
20 + s + "' is " + s.charCodeAt( 0 ) + "</p>" );
21
22 document.writeln( "<p>'" +
23 String.fromCharCode( 87, 79, 82, 68 ) +
24 "' contains character codes 87, 79, 82 and 68</p>" )
25

26 document.writeln( "<p>'" + s2 + "' in lowercase is '" +
27 s2.toLowerCase() + "'" );
28 document.writeln( "<br />'" + s2 + "' in uppercase is '"
29 + s2.toUpperCase() + "'</p>" );
30 // -->
31 </script>
32
33 </head><body></body>
34 </html>

Searching Methods
 indexOf and lastIndexOf
 Search for a specified substring in a string

SearchingStrings
.html
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6 
7
9 <head>
10 <title>
11 Searching Strings with indexOf and lastIndexOf
12 </title>
13
15 <!--
16 var letters = "abcdefghijklmnopqrstuvwxyzabcdefghijklm";
17
18 function buttonPressed()
19 {
20 searchForm.first.value =
21 letters.indexOf( searchForm.inputVal.value );
22 searchForm.last.value =
23 letters.lastIndexOf( searchForm.inputVal.value );
24 searchForm.first12.value =
25 letters.indexOf( searchForm.inputVal.value, 12 );

SearchingStrings
.html
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26 searchForm.last12.value =
27 letters.lastIndexOf(
28 searchForm.inputVal.value, 12 );
29 }
30 // -->
31 </script>
32
33 </head>
34 <body>
35 <form name = "searchForm" action = "">
36 <h1>The string to search is:<br />
37 abcdefghijklmnopqrstuvwxyzabcdefghijklm</h1>
38 <p>Enter substring to search for
39 <input name = "inputVal" type = "text" />
40 <input name = "search" type = "button" value = "Search"
41 onclick = "buttonPressed()" /><br /></p>
42
43 <p>First occurrence located at index
44 <input name = "first" type = "text" size = "5" />
45 <br />Last occurrence located at index
46 <input name = "last" type = "text" size = "5" />
47 <br />First occurrence from index 12 located at index
48 <input name = "first12" type = "text" size = "5" />
49 <br />Last occurrence from index 12 located at index
50 <input name = "last12" type = "text" size = "5" /></p>

SearchingStrings
.html
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51 </form>
52 </body>
53 </html>

Splitting Strings and Obtaining
Substrings
Tokenization
 The process of breaking a string into tokens
Tokens
 Individual words
 Separated by delimiters

SplitAndSubString
.html
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9 <head>
10 <title>String Method split and substring</title>
11
13 
23 </script>
24 </head>
25

SplitAndSubString
.html
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26 <body>
27 <form name = "myForm" action = "">
28 <p>Enter a sentence to split into words<br />
29 <input name = "inputVal" type = "text" size = "40" />
30 <input name = "splitButton" type = "button" value =
31 "Split" onclick = "splitButtonPressed()" /></p>
32
33 <p>The sentence split into words is<br />
34 <textarea name = "output" rows = "8" cols = "34">
35 </textarea></p>
36
37 <p>The first 10 characters of the input string are
38 <input name = "outputSubstring" type = "text"
39 size = "15" /></p>
40 </form>
41 </body>
42 </html>

XHTML Markup Methods
 Anchor
 <a name = “top”> Anchor </a>
 Blink
 <blink> blinking text </blink>
 Fixed
 <tt> monospaced text </tt>
 Strike
 <strike> strike out text </strike>
 Subscript
 <sub> subscript </sub>
 Superscript
 <sup> superscript </sup>

MarkupMethods.ht
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6 
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9 <head>
10 <title>XHTML Markup Methods of the String Object</title>
11
13 <!--
14 var anchorText = "This is an anchor",
15 blinkText = "This is blinking text",
16 fixedText = "This is monospaced text",
17 linkText = "Click here to go to anchorText",
18 strikeText = "This is strike out text",
19 subText = "subscript",
20 supText = "superscript";
21
22 document.writeln( anchorText.anchor( "top" ) );
23 document.writeln( "<br />" + blinkText.blink() );
24 document.writeln( "<br />" + fixedText.fixed() );
25 document.writeln( "<br />" + strikeText.strike() );

26 document.writeln(
27 "<br />This is text with a " + subText.sub() );
29 "<br />This is text with a " + supText.sup() );
31 "<br />" + linkText.link( "#top" ) );
32 // -->
33 </script>
34
36 </html>

Date Object
Provides methods for date and time
manipulations

Date Object
Method Description
getDate()
getUTCDate()
Returns a number from 1 to 31 representing the day of the month in local time or UTC, respectively.
getDay()
getUTCDay()
Returns a number from 0 (Sunday) to 6 (Saturday) representing the day of the week in local time or UTC,
respectively.
getFullYear()
getUTCFullYear()
Returns the year as a four-digit number in local time or UTC, respectively.
getHours()
getUTCHours()
Returns a number from 0 to 23 representing hours since midnight in local time or UTC, respectively.
getMilliseconds()
getUTCMilliSeconds()
Returns a number from 0 to 999 representing the number of milliseconds in local time or UTC, respectively.
The time is stored in hours, minutes, seconds and milliseconds.
getMinutes()
getUTCMinutes()
Returns a number from 0 to 59 representing the minutes for the time in local time or UTC, respectively.
getMonth()
getUTCMonth()
Returns a number from 0 (January) to 11 (December) representing the month in local time or UTC,
respectively.
getSeconds()
getUTCSeconds()
Returns a number from 0 to 59 representing the seconds for the time in local time or UTC, respectively.
getTime() Returns the number of milliseconds between January 1, 1970 and the time in the Date object.
getTimezoneOffset() Returns the difference in minutes between the current time on the local computer and UTC—previously
known as Greenwich Mean Time (GMT).
setDate( val )
setUTCDate( val )
Sets the day of the month (1 to 31) in local time or UTC, respectively.
Fig. 12.8 Methods of the Date object.

12.5 Date Object
Method Description
setFullYear( y, m, d )
setUTCFullYear( y, m, d )
Sets the year in local time or UTC, respectively. The second and third
arguments representing the month and the date are optional. If an optional
argument is not specified, the current value in the Date object is used.
setHours( h, m, s, ms )
setUTCHours( h, m, s, ms )
Sets the hour in local time or UTC, respectively. The second, third and fourth
arguments representing the minutes, seconds and milliseconds are optional. If
an optional argument is not specified, the current value in the Date object is
used.
setMilliSeconds( ms )
setUTCMilliseconds( ms )
Sets the number of milliseconds in local time or UTC, respectively.
setMinutes( m, s, ms )
setUTCMinutes( m, s, ms )
Sets the minute in local time or UTC, respectively. The second and third
arguments representing the seconds and milliseconds are optional. If an
optional argument is not specified, the current value in the Date object is
used.
setMonth( m, d )
setUTCMonth( m, d )
Sets the month in local time or UTC, respectively. The second argument
representing the date is optional. If the optional argument is not specified, the
current date value in the Date object is used.
setSeconds( s, ms )
setUTCSeconds( s, ms )
Sets the second in local time or UTC, respectively. The second argument
representing the milliseconds is optional. If this argument is not specified, the
current millisecond value in the Date object is used.

Date Object
Method Description
setTime( ms ) Sets the time based on its argument—the number of elapsed milliseconds
since January 1, 1970.
toLocaleString() Returns a string representation of the date and time in a form specific to the
computer’s locale. For example, September 13, 2001 at 3:42:22 PM is
represented as 09/13/01 15:47:22 in the United States and 13/09/01
15:47:22 in Europe.
toUTCString() Returns a string representation of the date and time in the form: 19 Sep
2001 15:47:22 UTC
toString() Returns a string representation of the date and time in a form specific to the
locale of the computer (Mon Sep 19 15:47:22 EDT 2001 in the United
States).
valueOf() The time in number of milliseconds since midnight, January 1, 1970.

DateTime.html
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5 
6 
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9 <head>
10 <title>Date and Time Methods</title>
11
13 <!--
14 var current = new Date();
15
17 "<h1>String representations and valueOf</h1>" );
18 document.writeln( "toString: " + current.toString() +
19 "<br />toLocaleString: " + current.toLocaleString() +
20 "<br />toUTCString: " + current.toUTCString() +
21 "<br />valueOf: " + current.valueOf() );
22
24 "<h1>Get methods for local time zone</h1>" );

DateTime.html
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25 document.writeln( "getDate: " + current.getDate() +
26 "<br />getDay: " + current.getDay() +
27 "<br />getMonth: " + current.getMonth() +
28 "<br />getFullYear: " + current.getFullYear() +
29 "<br />getTime: " + current.getTime() +
30 "<br />getHours: " + current.getHours() +
31 "<br />getMinutes: " + current.getMinutes() +
32 "<br />getSeconds: " + current.getSeconds() +
33 "<br />getMilliseconds: " +
34 current.getMilliseconds() +
35 "<br />getTimezoneOffset: " +
36 current.getTimezoneOffset() );
37
39 "<h1>Specifying arguments for a new Date</h1>" );
40 var anotherDate = new Date( 2001, 2, 18, 1, 5, 0, 0 );
41 document.writeln( "Date: " + anotherDate );
42
44 "<h1>Set methods for local time zone</h1>" );
45 anotherDate.setDate( 31 );
46 anotherDate.setMonth( 11 );
47 anotherDate.setFullYear( 2001 );
48 anotherDate.setHours( 23 );
49 anotherDate.setMinutes( 59 );

50 anotherDate.setSeconds( 59 );
51 document.writeln( "Modified date: " + anotherDate );
52 // -->
53 </script>
54
56 </html>

Boolean and Number Objects
Object wrappers for boolean true/false
values and numbers

Method Description
toString() Returns the string “true” if the value of the Boolean object is
true; otherwise, returns the string “false.”
valueOf() Returns the value true if the Boolean object is true; otherwise,
returns false.
Fig. 12.10 Boolean object methods.

Method or Property Description
toString( radix ) Returns the string representation of the number. The optional radix
argument (a number from 2 to 36) specifies the number’s base. For
example, radix 2 results in the binary representation of the number,
8 results in the octal representation, 10 results in the decimal
representation and 16 results in the hexadecimal representation.
See Appendix E, Number Systems for a review of the binary, octal,
decimal and hexadecimal number systems.
valueOf() Returns the numeric value.
Number.MAX_VALUE This property represents the largest value that can be stored in a
JavaScript program—approximately 1.79E+308
Number.MIN_VALUE This property represents the smallest value that can be stored in a
JavaScript program—approximately
2.22E–308
Number.NaN This property represents not a number—a value returned from an
arithmetic expression that does not result in a number (e.g., the
expression parseInt( "hello" ) cannot convert the string
"hello" into a number, so parseInt would return
Number.NaN. To determine whether a value is NaN, test the
result with function isNaN, which returns true if the value is
NaN; otherwise, it returns false.
Number.NEGATIVE_INFINITY This property represents a value less than
-Number.MAX_VALUE.
Number.POSITIVE_INFINITY This property represents a value greater than
Number.MAX_VALUE.
Fig. 12.11 Number object methods and properties.

document Object
Manipulate document that is currently
visible in the browser window

document Object
write( string ) Writes the string to the XHTML document as
XHTML code.
writeln( string ) Writes the string to the XHTML document as
XHTML code and adds a newline character at
the end.
document.cookie This property is a string containing the values
of all the cookies stored on the user’s computer
for the current document. See Section 12.9,
Using Cookies.
document.lastModified This property is the date and time that this
document was last modified.
Fig. 12.12 Important document object methods and properties.

window Object
Provides methods for manipulating
browser window

window.html
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1 <?xml version = "1.0" encoding = "utf-8"?>
2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
3 "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
4
5 
6 
7
9 <head>
10 <title>Using the Window Object</title>
11
13 <!--
14 var childWindow; // variable to control the child window
15
16 function createChildWindow()
17 {
18 // these variables all contain either "yes" or "no"
19 // to enable or disable a feature in the child window
20 var toolBar // specify if toolbar will appear in child window
21 var menuBar; // specify if menubar will appear in child window
22 var location; // specify if address bar will appear in child window
23 var scrollBars; // specify if scrollbars will appear in child window
24 var status; // specify if status bar will appear in child window
25 var resizable; // specify if the child window will be resizable

window.html
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26
27 // determine whether the Tool Bar checkbox is checked
28 if ( toolBarCheckBox.checked )
29 toolBar = "yes";
30 else
31 toolBar = "no";
32
33 // determine whether the Menu Bar checkbox is checked
34 if ( menuBarCheckBox.checked )
35 menuBar = "yes";
36 else
37 menuBar = "no";
38
39 // determine whether the Address Bar checkbox is checked
40 if ( locationCheckBox.checked )
41 location = "yes";
42 else
43 location = "no";
44
45 // determine whether the Scroll Bar checkbox is checked
46 if ( scrollBarsCheckBox.checked )
47 scrollBars = "yes";
48 else
49 scrollBars = "no";
50

window.html
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51 // determine whether the Status Bar checkbox is checked
52 if ( statusCheckBox.checked )
53 status = "yes";
54 else
55 status = "no";
56
57 // determine whether the Resizable checkbox is checked
58 if ( resizableCheckBox.checked )
59 resizable = "yes";
60 else
61 resizable = "no";
62
63 // display window with selected features
64 childWindow = window.open( "", "", "resizable = " + resizable +
65 ", toolbar = " + toolBar + ", menubar = " + menuBar +
66 ", status = " + status + ", location = " + location +
67 ", scrollbars = " + scrollBars );
68
69 // disable buttons
70 closeButton.disabled = false;
71 modifyButton.disabled = false;
72 getURLButton.disabled = false;
73 setURLButton.disabled = false;
74 } // end function createChildWindow
75

window.html
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76 // insert text from the textbox into the child window
77 function modifyChildWindow()
78 {
79 if ( childWindow.closed )
80 alert( "You attempted to interact with a closed window" );
81 else
82 childWindow.document.write( textForChild.value );
83 } // end function modifyChildWindow
84
85 // close the child window
86 function closeChildWindow()
87 {
90 else
91 childWindow.close();
92
93 closeButton.disabled = true;
94 modifyButton.disabled = true;
95 getURLButton.disabled = true;
96 setURLButton.disabled = true;
97 } // end function closeChildWindow
98

window.html
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99 // copy the URL of the child window into the parent window’s myChildURL
100 function getChildWindowURL()
101 {
104 else
105 myChildURL.value = childWindow.location;
106 } // end function getChildWindowURL
107
108 // set the URL of the child window to the URL
109 // in the parent window’s myChildURL
110 function setChildWindowURL()
111 {
114 else
115 childWindow.location = myChildURL.value;
116 } // end function setChildWindowURL
117 //-->
118 </script>
119
120 </head>
121
122 <body>
123 <h1>Hello, This is the main window</h1>

window.html
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124 <p>Please check the features to enable for the child window<br/>
125 <input id = "toolBarCheckBox" type = "checkbox" value = ""
126 checked = "checked" />
127 <label>Tool Bar</label>
128 <input id = "menuBarCheckBox" type = "checkbox" value = ""
130 <label>Menu Bar</label>
131 <input id = "locationCheckBox" type = "checkbox" value = ""
133 <label>Address Bar</label><br/>
134 <input id = "scrollBarsCheckBox" type = "checkbox" value = ""
136 <label>Scroll Bars</label>
137 <input id = "statusCheckBox" type = "checkbox" value = ""
139 <label>Status Bar</label>
140 <input id = "resizableCheckBox" type = "checkbox" value = ""
142 <label>Resizable</label><br/></p>
143
144 <p>Please enter the text that you would like to display
145 in the child window<br/>
146 <input id = "textForChild" type = "text"
147 value = "<h1> Hello, I am a child window</h1> <br>"/>

window.html
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148 <input id = "createButton" type = "button"
149 value = "Create Child Window" onclick = "createChildWindow()" />
150 <input id= "modifyButton" type = "button" value = "Modify Child Window"
151 onclick = "modifyChildWindow()" disabled = "disabled"/>
152 <input id = "closeButton" type = "button" value = "Close Child Window"
153 onclick = "closeChildWindow()" disabled = "disabled"/></p>
154
155 <p>The other window's URL is: <br/>
156 <input id = "myChildURL" type = "text" value = "./"/>
157 <input id = "setURLButton" type = "button" value = "Set Child URL"
158 onclick = "setChildWindowURL()" disabled = "disabled"/>
159 <input id = "getURLButton" type = "button" value = "Get URL From Child"
160 onclick = "getChildWindowURL()" disabled = "disabled"/></p>
161
162 </body>
163 </html>

window Object
open( url, name, options ) Creates a new window with the URL of the window set to
url, the name set to name, and the visible features set by
the string passed in as option.
prompt( prompt, default ) Displays a dialog box asking the user for input. The text
of the dialog is prompt, and the default value is set to
default.
close() Closes the current window and deletes its object from
memory.
window.focus() This method gives focus to the window (i.e., puts the
window in the foreground, on top of any other open
browser windows).
window.document This property contains the document object representing
the document currently inside the window.
window.closed This property contains a boolean value that is set to true if
the window is closed, and false if it is not.
window.opener This property contains the window object of the window
that opened the current window, if such a window exists.
Fig. 12.14 Important window object methods and properties.

Using Cookies
Cookie
 Data stored on user’s computer to maintain
information about client during and between
browser sessions
 Can be accessed through cookie property
 Set expiration date through expires property
 Use escape function to convert non-
alphanumeric characters to hexadecimal
escape sequences
 unescape function converts hexadecimal
escape sequences back to English characters

cookie.html
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9 <head>
10 <title>Using Cookies</title>
11
13 <!--
14 var now = new Date(); // current date and time
15 var hour = now.getHours(); // current hour (0-23)
16 var name;
17
18 if ( hour < 12 ) // determine whether it is morning
19 document.write( "<h1>Good Morning, " );
20 else
21 {
22 hour = hour - 12; // convert from 24 hour clock to PM time
23

cookie.html
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24 // determine whether it is afternoon or evening
25 if ( hour < 6 )
26 document.write( "<h1>Good Afternoon, " );
27 else
28 document.write( "<h1>Good Evening, " );
29 }
30
31 // determine whether there is a cookie
32 if ( document.cookie )
33 {
34 // convert escape characters in the cookie string to their
35 // english notation
36 var myCookie = unescape( document.cookie );
37
38 // split the cookie into tokens using = as delimiter
39 var cookieTokens = myCookie.split( "=" );
40
41 // set name to the part of the cookie that follows the = sign
42 name = cookieTokens[ 1 ];
43 }
44 else
45 {
46 // if there was no cookie then ask the user to input a name
47 name = window.prompt( "Please enter your name", "GalAnt" );
48

cookie.html
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49 // escape special characters in the name string
50 // and add name to the cookie
51 document.cookie = "name=" + escape( name );
52 }
53
55 name + ", welcome to JavaScript programming! </h1>" );
56 document.writeln( "<a href= " JavaScript:wrongPerson() " > " +
57 "Click here if you are not " + name + "</a>" );
58
59 // reset the document's cookie if wrong person
60 function wrongPerson()
61 {
62 // reset the cookie
63 document.cookie= "name=null;" +
64 " expires=Thu, 01-Jan-95 00:00:01 GMT";
65
66 // after removing the cookie reload the page to get a new name
67 location.reload();
68 }
69
70 // -->
71 </script>
72 </head>
73

74 <body>
75 <p>Click Refresh (or Reload) to run the script again</p>
76 </body>
77 </html>

Final JavaScript Example
Combines concepts discussed previously

final.html
1 of 6
4
5 
6 
7
9 <head>
10 <title>Putting It All Together</title>
11
13 <!--
14 var now = new Date(); // current date and time
15 var hour = now.getHours(); // current hour
16
17 // array with names of the images that will be randomly selected
18 var pictures =
19 [ "CPE", "EPT", "GPP", "GUI", "PERF", "PORT", "SEO" ];
20
21 // array with the quotes that will be randomly selected
22 var quotes = [ "Form ever follows function.<br/>" +
23 " Louis Henri Sullivan", "E pluribus unum." +
24 " (One composed of many.) <br/> Virgil", "Is it a" +
25 " world to hide virtues in?<br/> William Shakespeare" ];

final.html
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26
27 // write the current date and time to the web page
28 document.write( "<p>" + now.toLocaleString() + "<br/></p>" );
29
30 // determine whether it is morning
31 if ( hour < 12 )
32 document.write( "<h2>Good Morning, " );
33 else
34 {
35 hour = hour - 12; // convert from 24 hour clock to PM time
36
37 // determine whether it is afternoon or evening
38 if ( hour < 6 )
39 document.write( "<h2>Good Afternoon, " );
40 else
41 document.write( "<h2>Good Evening, " );
42 }
43
44 // determine whether there is a cookie
45 if ( document.cookie )
46 {
47 // convert escape characters in the cookie string to their
48 // english notation
49 var myCookie = unescape( document.cookie );
50

final.html
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51 // split the cookie into tokens using = as delimiter
52 var cookieTokens = myCookie.split( "=" );
53
54 // set name to the part of the cookie that follows the = sign
55 name = cookieTokens[ 1 ];
56 }
57 else
58 {
59 // if there was no cookie then ask the user to input a name
60 name = window.prompt( "Please enter your name", "GalAnt" );
61
62 // escape special characters in the name string
63 // and add name to the cookie
64 document.cookie = "name =" + escape( name );
65 }
66
67 // write the greeting to the page
69 name + ", welcome to JavaScript programming!</h2>" );
70
71 // write the link for deleting the cookie to the page
72 document.writeln( "<a href = " JavaScript:wrongPerson() " > " +
73 "Click here if you are not " + name + "</a><br/>" );
74

final.html
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75 // write the random image to the page
76 document.write ( "<img src = "" +
77 pictures[ Math.floor( Math.random() * 7 ) ] +
78 ".gif" width= " 105 " height= " 100 " /> <br/>" );
79
80 // write the random quote to the page
81 document.write ( quotes[ Math.floor( Math.random() * 3 ) ] );
82
83 // create a window with all the quotes in it
84 function allQuotes()
85 {
86 // create the child window for the quotes
87 quoteWindow = window.open( "", "", "resizable=yes, toolbar" +
88 "=no, menubar=no, status=no, location=no," +
89 " scrollBars=yes" );
90 quoteWindow.document.write( "<p>" )
91
92 // loop through all quotes and write them in the new window
93 for ( var i = 0; i < quotes.length; i++ )
94 quoteWindow.document.write( ( i + 1 ) + ".) " +
95 quotes[ i ] + "<br/><br/>");
96

final.html
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97 // write a close link to the new window
98 quoteWindow.document.write( "</p><br/><a href = " " +
99 "JavaScript:window.close()">" +
100 " Close this window </a>" )
101 }
102
103 // reset the document's cookie if wrong person
104 function wrongPerson()
105 {
106 // reset the cookie
107 document.cookie= "name=null;" +
108 " expires=Thu, 01-Jan-95 00:00:01 GMT";
109
110 // after removing the cookie reload the page to get a new name
111 location.reload();
112 }
113
114 // open a new window with the quiz2.html file in it
115 function openQuiz()
116 {
117 window.open( "quiz2.html", "", "resizable = yes, " +
118 "toolbar = no, menubar = no, status = no, " +
119 "location = no, scrollBars = no");
120 }
121 // -->

final.html
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122 </script>
123
124 </head>
125
126 <body>
127 <p><a href = "JavaScript:allQuotes()">View all quotes</a></p>
128
129 <p id = "quizSpot">
130 <a href = "JavaScript:openQuiz()">Please take our quiz</a></p>
131
133 // variable that gets the last midification date and time
134 var modDate = new Date( document.lastModified );
135
136 // write the last modified date and time to the page
137 document.write ( "This page was last modified " +
138 modDate.toLocaleString() );
139 </script>
140
141 </body>
142 </html>

quiz2.html
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1 <?xml version = "1.0" encoding = "utf-8"?>
4
5 
6 
7
9 <head>
10 <title>Online Quiz</title>
11
12 <script type = "text/JavaScript">
13 <!--
14 function checkAnswers()
15 {
16 // determine whether the answer is correct
17 if ( myQuiz.radiobutton[ 1 ].checked )
18 window.opener.quizSpot.innerText =
19 "Congratulations, your answer is correct";
20 else // if the answer is incorrect
21 window.opener.quizSpot.innerHTML = "Your answer is incorrect." +
22 " Please try again <br /> <a href= " JavaScript:openQuiz()" +
23 " " > Please take our quiz</a>";
24
25 window.opener.focus();

quiz2.html
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26 window.close();
27 } // end checkAnswers function
28 //-->
29 </script>
30
31 </head>
32
33 <body>
34 <form id = "myQuiz" action = "JavaScript:checkAnswers()">
35 <p>Select the name of the tip that goes with the image shown:<br />
36 <img src = "EPT.gif" width = "108" height = "100"
37 alt = "mystery tip"/>
38 <br />
39
40 <input type = "radio" name = "radiobutton" value = "CPE" />
41 <label>Common Programming Error</label>
42
43 <input type = "radio" name = "radiobutton" value = "EPT" />
44 <label>Error-Prevention Tip</label>
45
46 <input type = "radio" name = "radiobutton" value = "PERF" />
47 <label>Performance Tip</label>
48
49 <input type = "radio" name = "radiobutton" value = "PORT" />
50 <label>Portability Tip</label><br />

51
52 <input type = "submit" name = "Submit" value = "Submit" />
53 <input type = "reset" name = "reset" value = "Reset" />
54 </p>
55 </form>
56 </body>
57 </html>

Assignment 10
 1) Exercise # 12.7. Due Date for A # 10:
 Next Monday before
your lecture.

JavaScript Objects

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