JavaScript

1
JavaScript
2
math Object

• abs
• math.abs(-80) is 80
• Many other functions

3
window Object

• The window object represents the browser window
• It doesnt have a name
• That is, there is no variable that contains a
  reference to it
• A reference to it is assumed when you use
  properties such as history or alert( )

4
window Object

• Most browsers allow more than one window open at
  a time
• Thus, implicit window reference refers only to
  the current window, the window that is displaying
  the HTML document that contains the JavaScript
  code currently being executed

5
window Object

• To refer to some other window, you must have a
  reference to it
• Use the open( ) method
• This is also a method of a document, so the
  syntax should be window.open( ) or self.open( )

6
window Object

• The Window object has a property named window and
  another named self
• Both, implicitly, contain references to the
  window itself
• window.history
• window.alert(Hello there!)

7
window Object

• The Window object has a property named window and
  another named self
• First argument of open( ) specifies URL of page
  to displayed, or an empty string to open a blank
  window
• var newwin open("otherpage.html")
• newwin.creator self

8
window Object

• Every JavaScript expression implicitly refers to
  the current window
• Thus, code like j 0 is actually the same as
  window.j 0
• Variables are nothing more than properties of the
  current window
• Two variables with same name can be declared in
  different windows or frames without conflicting
  with each other

9
window Object

• Every JavaScript expression implicitly refers to
  the current window
• JavaScript code running in one window or frame
  can read and write variables declared by code in
  another window
• Thus, if a top-level window has two frames and
  the following code in the first frame
• parent.frames1.j 7
• this is equivalent to the following code in the
  second frame
• j 7

10
window Object

• Every JavaScript expression implicitly refers to
  the current window
• No really global variables across window and
  frames

11
window Object

• Every JavaScript expression implicitly refers to
  the current window
• When a page that contains a script is unloaded
  due to the user pointing the browser to a new
  page, the script is unloaded along with the page
  that contains it
• What about the script variables?
• Since they are properties of the window object,
  you might think they are still defined

12
window Object

• Every JavaScript expression implicitly refers to
  the current window
• When a page that contains a script is unloaded
  due to the user pointing the browser to a new
  page, the script is unloaded along with the page
  that contains it
• If they were, however, this would be dangerous
• A new script that was loaded would start off with
  some baggage

13
window Object

• Every JavaScript expression implicitly refers to
  the current window
• When a page that contains a script is unloaded
  due to the user pointing the browser to a new
  page, the script is unloaded along with the page
  that contains it
• All user-defined properties (which includes all
  variables) are erased whenever a page is unloaded
• The lifetime of scripts and of the variables they
  define is the same as the lifetime of the
  document object that contains the script

14
window Object

• Garbage collection
• JavaScript supports automatic garbage collection
• Different techniques in Navigator 2.0, Navigator
  3.0, and Navigator 4

15
window Object

• Garbage collection
• Navigator 4 / JavaScript 1.2
• Completely transparent

16
window Object

• Navigator 3.0 / JavaScript 1.1
• Uses reference counts
• If JavaScript code running in a window object
  creates an object, o, and a reference to that
  object is stored in a variable of another window
  object, then o will continue to exist even after
  the window object that created it is closed or
  loads in a different page

17
window Object

• Navigator 3.0 / JavaScript 1.0
• A top-level window may be closed by the user, but
  the window object associated with it may continue
  to exist if a variable in another window object
  contains a reference to the window object that is
  closed

18
window Object

• Navigator 2.0
• All objects created by JavaScript code running in
  a particular window object allocate memory from a
  pool owned by the window object
• When the window object is destroyed or when the
  document object containing the JavaScript program
  displayed in the window is unloaded, the entire
  pool of memory is freed at once

19
window Object

• Navigator 2.0
• Disadvantages
• If an object is created in one window and a
  reference to that object is stored in a variable
  in a second window, that object will be destroyed
  when the first window moves on to a new page,
  even though there is an active reference to it
• If the other window tries to use this reference,
  an error will result, possibly resulting in a
  browser crash

20
window Object

• Navigator 2.0
• Disadvantages
• If a window never unloads, its associated memory
  will never be freed
• One frame may serve as a navigation window
  allowing users to browse a large site in other
  frames or windows
• These other frames or windows may load and unload
  pages frequently, but the navigation frame
  remains the same

21
window Object

• Properties
• closed
• Read-only boolean specifying whether window
  object is closed
• defaultStatus
• String specifying default message appearing in
  status line
• document
• Reference to document object contained in window
  object

22
window Object

• Properties
• frames
• An array of frame objects contained by this
  window object
• history
• A reference to the history object for this window
  object
• length
• The number of elements in the frames array
  read-only

23
window Object

• Properties
• location
• A reference to the location object for this
  window object
• name
• String specifying name of the window object
• navigator
• A reference to the navigator object that applies
  to this and all other window objects

24
window Object

• Properties
• opener
• A reference to the window object that called
  open() to create this window object
• parent
• A reference to the parent window (frame) object
  of the current window object
• self
• A reference to the window object itself

25
window Object

• Properties
• status
• A string specifying the current contents of the
  status bar
• top
• A reference to the top-level window object that
  contains the current window object
• window
• A reference to the current window object

26
window Object

• Methods
• alert()
• Display a simple message in a dialog box
• window.alert(message)
• Displays message in a dialog box
• Dialog box contains an OK button that user can
  click to dismiss it
• User can continue to interact with browser window
  while the dialog is displayed
• JavaScript execution continues while the dialog
  is displayed
• Used to display error messages
• message is plain text, so can use newline
  characters to break your message across multiple
  lines

27
window Object

• Methods
• blur()
• window.blur()
• Takes keyboard focus from browser window
  specified by the window object
• If this object is a frame object, then keyboard
  focus is given to the toplevel window object
  containing the frame object
• The window object will be sent to the background,
  to the bottom of the window stack

28
window Object

• Methods
• clearTimeout()
• window.clearTimeout(timeoutId)
• Cancels the execution of code that has been
  deferred with the setTimeout() method
• The timeoutId argument is a value returned by the
  call to setTimeout() and specifies which block of
  deferred code to cancel

29
window Object

• Methods
• close()
• window.close()
• Closes browser window specified by window
• A window object can close itself by issuing
  self.close() or close()
• If window is the only open window object, then it
  is closed and browser exits
• In Navigator 3.0, only window objects opened by
  JavaScript can be closed by JavaScript

30
window Object

• Methods
• confirm()
• window.confirm(question)
• Displays argument question in a dialog box that
  pops up over window
• Dialog contains OK and Cancel buttons
• If user clicks OK, then confirm() returns true
• If user clicks Cancel, the confirm() returns
  false
• Blocks all user input to the browser window until
  user dismisses dialog by clicking on the OK or
  Cancel buttons

31
window Object

• Methods
• confirm()
• JavaScript execution pauses until user response
• The string question is plain text, so can use
  newline characters

32
window Object

• Methods
• focus()
• window.focus()
• Gives keyboard focus to browser window specified
  by window object
• If window object is a frame, then keyboard focus
  is given to top-level window that contains that
  frame
• When window object is given focus, it is brought
  forward, to top of window stack

33
window Object

• Methods
• open()
• window.open(url, name, features)
• url is string specifying url to be displayed in
  the new window, or the empty string for a blank
  window
• name is a string specifying name for the new
  window object
• This name can be used as value of the target
  attribute of the ltagt (window which displays
  result of clicking on link), ltmapgt (window which
  displays result of clicking on image), and ltformgt
  tags (window which displays result of form
  submission)

34
window Object

• Methods
• open()
• window.open(url, name, features)
• features is a string specifying features of
  browser window
• If not specified, then new window object will
  have all standard features

35
window Object

• Methods
• open()
• Returns a reference to a window object, either
  newly created or an existing one
• If the name argument specifies an existing window
  object, then a reference to that window object is
  returned
• The returned window object will display the url
  specified by url, but the features argument will
  be ignored

36
window Object

• Methods
• open()
• If the name argument is not specified, or no
  window object with that name already exists, a
  new window object is created
• The created window object displays the url
  specified by url and the size and controls
  specified by features
• The name of the new window object is specified by
  name

37
window Object

• Methods
• open()
• The features argument is a comma-separated list
  with the format featurevalue
• For most features, value is yes or no
• If feature appears and value is omitted, yes is
  assumed
• If feature doesn't appear, no is assumed
• toolbar
• Browser toolbar with Back and Forward buttons

38
window Object

• Methods
• open()
• The features argument is a comma-separated list
  with the format featurevalue
• location
• The input field for entering URL's directly into
  the browser
• directories
• Directory buttons, such as "What's New" and
  "What's Cool" in Netscape
• status
• The status line

39
window Object

• Methods
• open()
• The features argument is a comma-separated list
  with the format featurevalue
• menubar
• The menu bar
• scrollbars
• Enables horizontal and vertical scrollbars when
  necessary
• resizable
• window object will have resize handles around its
  border

40
window Object

• Methods
• open()
• The features argument is a comma-separated list
  with the format featurevalue
• width
• Width of window object in pixels
• height
• Height of window object in pixels

41
window Object

• Methods
• prompt()
• window.prompt(message)
• window.prompt(message, default)
• Displays specified message in a dialog box that
  also contains a textual input field and OK,
  Clear, and Cancel buttons
• If user clicks Cancel, prompt() returns null
• If user clicks Clear, prompt() erases any text in
  the input field
• If user clicks OK, prompt() returns the current
  value displayed in the input field (as a string)

42
window Object

• Methods
• prompt()
• The default argument specifies text that
  initially appears in the input field
• Blocks all user input to the browser window until
  user dismisses dialog by clicking on the OK or
  Cancel buttons
• JavaScript execution pauses until user response

43
window Object

• Methods
• scroll()
• window.scroll(x,y)
• Moves the window object's document object within
  the window object, so that the specified x and y
  coordinates of the document object appear in the
  upper-left corner of the window object
• scroll(0,0) places the top-left of the document
  object in the top-left corner of the window object

44
window Object

• Methods
• setTimeout()
• window.setTimeout(code, delay)
• Returns a timeout-id that can be passed to the
  clearTimeout() method to cancel the execution of
  code
• Defers execution of code for delay milliseconds

45
window Object

• Event handlers
• onblur()
• ltbody
• onBlur "JavaScript statements"
• gt
• ltframeset
• onBlur "JavaScript statements"
• gt

46
window Object

• Event handlers
• onblur()
• window.onblur handler_function
• Defining the handler directly
• window.onblur()
• An explicit invocation of the handler

47
window Object

• Event handlers
• onblur()
• Invoked by browser when browser window loses the
  input focus, either because the user has switched
  to some other window object, or because focus was
  explicitly transferred to another browser window
  with the window object blur() or focus() methods

48
window Object

• Methods
• onerror()
• window.onerror handler_function
• Defining the error handler
• window.onerror(message, url, line)
• Invoking the error handler
• Customizing error handling
• message specifies the error message for the error
  that occurred

49
window Object

• Methods
• onerror()
• url specifies the URL of the document object in
  which the error occurred
• line specifies the line number at which the error
  occurred

50
window Object

• Methods
• onfocus()
• ltbody
• onFocus "JavaScript statements"
• gt
• ltframeset
• onFocus "JavaScript statements"
• gt

51
window Object

• Methods
• onfocus()
• window.onfocus handler_function
• Defining the handler directly
• window.onfocus()
• An explicit invocation of the handler

52
window Object

• Methods
• onfocus()
• Invoked by browser when browser window is given
  the input focus, either because the user has
  switched to this window object, or because focus
  was explicitly transferred to this browser window
  with the window object focus() method

53
window Object

• Methods
• onload()
• ltbody onLoad "JavaScript
• statements"
• gt
• ltframeset rows "row sizes"
• cols "column sizes"
• onLoad "JavaScript statements"gt

54
window Object

• Methods
• onload()
• window.onload
• Reference to handler
• window.onload()
• Explicit invocation of handler
• Can use this handler to set a variable and to
  check the value of this variable before doing
  anything that depends on the complete document
  object being loaded

55
window Object

• Methods
• onunload()
• ltbody onUnload "JavaScript
• statements"
• gt
• ltframeset rows "row sizes"
• cols "column sizes"
• onUnload "JavaScript statements"gt

56
window Object

• Methods
• onunload()
• window.onunload
• Reference to handler
• window.onunload()
• Explicit invocation of handler
• Can use this handler to set a variable and to
  check the value of this variable before doing
  anything that depends on the complete document
  object being loaded

57
document Object

• Notation
• window.document
• document

58
document Object

• Properties
• alinkColor
• Specifies color of activated links
• anchors
• Array of anchor objects, one for each hypertext
  target
• document.anchorsj or document .anchor-name
• anchors.length
• Number of elements in anchors read-only

59
document Object

• Properties
• applets
• An array of Java objects, one for each
  ltappletgt-tag
• applets.length
• Number of elements in applets
• bgColor
• A string specifying the background color
• cookie
• A string that specifies the value of a cookie

60
document Object

• Properties
• domain
• A string that specifies the domain of the
  document object
• embeds
• An array of Java objects, one for each
  ltembedgt-tag
• embeds.length
• Number of elements in embeds read-only

61
document Object

• Properties
• fgColor
• A string specifying the color of document text
• forms
• An array of forms objects, one for each
  ltformgt-tag
• document.formsj or document .form_name
• forms.length
• Number of elements in forms read-only

62
document Object

• Properties
• images
• An array of image objects, one for each image
  embedded in the document using the ltimggt-tag
• document.imagesi or document .image_name
• images.length
• Number of elements in images read-only
• lastModified
• Read-only string that specifies date of most
  recent document change

63
document Object

• Properties
• linkColor
• A string specifying color unvisited links
• links
• An array of link objects, one for each hypertext
  link
• links.length
• Number of elements in links read-only

64
document Object

• Properties
• location
• A synonym for the URL property
• plugins
• A synonym for the embeds array
• plugins.length
• A synonym for embeds.length

65
document Object

• Properties
• referrer
• A read-only string specifying the URL of the
  document object that contained the link that
  referred to the current document
• title
• A read-only string specifying the lttitlegt of the
  document object

66
document Object

• Properties
• URL
• A read-only string specifying the URL of the
  document object
• vlinkColor
• A string specifying the color of visited links

67
document Object

• Methods
• clear( )
• Erases contents of document object
• close( )
• Closes a document stream opened with open()
  method
• open( )
• Opens a stream to which document object contents
  can be written

68
document Object

• Methods
• write( )
• Inserts the specified string into the document
  object currently being parsed, or into a document
  stream opened with open( )
• writeln( )
• Same as write but appends a newline character

69
document Object

• Event handlers
• onload
• Invoked when document is loaded
• Specified by onLoad attribute
• onunload
• Invoked when document is unloaded
• Specified by onUnload attribute

70
document Object

• HTML syntax
• ltbody
• background imageURL a background image
• bgcolor color a background color
• text color color of documents text
• link color color for unvisited links
• alink color color for activated links
• vlink color color for visited links
• onLoad handler onload event handler
• onUnload handler onunload event handler
• gt

71
form Object

• Notation
• document.form_name
• document.formsform_number
• document.forms.length

72
form Object

• Properties
• action
• A string specifying the URL to which the form
  object is to be submitted
• elements
• An array of input elements that appear in the
  form object
• Each element is a button, checkbox, hidden,
  password, radio, reset, select, submit, text, or
  textarea object

73
form Object

• Properties
• elements.length
• Number of items in elements
• encoding
• String specifying the encoding method for form
  data
• method
• String specifying technique for submitting form
• target
• String specifying name of frame of window in
  which results of submitting form should be
  displayed

74
form Object

• Methods
• reset( )
• Reset each of the input elements of the form to
  their default values
• submit( )
• Submit the form

75
form Object

• Event handlers
• onreset( )
• Invoked just before elements of form are reset
• Specified by onReset attribute
• onsubmit( )
• Invoked just before form is submitted
• Specified by onSubmit attribute

76
form Object

• HTML syntax
• ltform
• name form_name name of the form in
• JavaScript
• target window_name name of response
  window
• action url submitted-to URL
• method (get post) method of form
• submission
• enctype encoding how form data is encoded
• onSubmit handler onsubmit( ) event handler
• onReset handler onreset( ) event handler
• gt

77
button Object

• Notation
• form.button_name
• form.elementsj
• form.elementsbutton_name

78
button Object

• Properties
• form
• Read-only reference to form object that contains
  button object
• name
• Read-only string specifying name of the button
  object
• type
• Read-only string specifying type of form element
• In this case, it is button

79
button Object

• Properties
• value
• Read-only string specifying value displayed in
  the button object

80
button Object

• Event handlers
• onclick( )
• Invoked when button is clicked

81
button Object

• HTML syntax
• ltinput
• type button specifies that this is a button
• value label text to appear within button
• name name name to refer to button
• onClick handler onclick( ) event handler
• gt

82
checkbox Object

• Notation
• Single checkbox
• form.checkbox_name
• form.elementsj
• form.elementscheckbox_name

83
checkbox Object

• Notation
• Group of checkboxes with same name
• form.checkbox_namej
• form.checkbox_name.length
• form.elementsjk
• form.elementsj.length
• form.elementscheckbox_namej
• formlelementscheckbox_name.length

84
checkbox Object

• Properties
• checked
• Boolean value specifying whether checkbox object
  is checked or not
• defaultChecked
• Boolean value specifying the initial state of
  checkbox object read-only
• form
• Read-only reference to form object containing
  checkbox object

85
checkbox Object

• Properties
• name
• Read-only string specifying name of checkbox
  object
• type
• Read-only string specifying type of form element
• In this case, it is checkbox
• value
• String specifying value returned by checkbox
  object if it is selected when form is submitted

86
checkbox Object

• Event handlers
• onclick( )
• Invoked when the checkbox is clicked

87
checkbox Object

• HTML syntax
• ltinput
• type checkbox specifies that this is checkbox
• name name name to refer to checkbox
• value value value returned when selected
• checked checkbox is initially checked
• onClick handler onclick( ) event handler
• gt

88
hidden Object

• Notation
• form.name
• form.elementsj
• form.elementsname

89
hidden Object

• Properties
• form
• Read-only reference to containing form object
• name
• Read-only string specifying name of hidden object
• type
• Read-only string specifying type of this form
  element
• In this case, it is hidden

90
hidden Object

• Properties
• value
• String specifying data to be transmitted to
  server when form is submitted

91
hidden Object

• HTML syntax
• ltinput
• type hidden specifies that this is hidden
  object
• name name name to refer to hidden object
• value value value transmitted when form
• submitted
• gt

92
password Object

• Notation
• form.name
• form.elementsj
• form.elementsname

93
password Object

• Properties
• form
• Read-only reference to form object containing
  password object
• name
• Read-only string specifying name of password
  object
• type
• Read-only string specifying type of form element
• In this case, it is password

94
password Object

• Properties
• value
• Read-only string specifying password value
  entered by user

95
password Object

• Methods
• blur( )
• Removes keyboard focus from password object
• focus( )
• Sets keyboard focus to password object
• When focus is set, all keystrokes are
  automatically entered into this object

96
password Object

• HTML syntax
• ltinput
• type password specifies this is password
  object
• name name name to refer to password object
• value default default value transmitted
  when
• form is submitted
• size integer number of characters wide of
  the
• object
• gt

97
radio Object

• Notation
• Always used in groups of mutually exclusive
  options that have same name
• form.radio_name
• form.radio_name.length
• form.elementsjk
• form.elementsj.length
• form.elementsradio_namek
• form.elementsradio_name.length

98
radio Object

• Properties
• checked
• Boolean value specifying whether button is
  checked or not
• defaultChecked
• Read-only Boolean value specifying initial state
  of radio object
• form
• Read-only reference to form object containing
  radio object

99
radio Object

• Properties
• name
• Read-only string specifying name of radio object
• type
• Read-only string specifying type of form element
• In this case, it is radio

100
radio Object

• Properties
• value
• String specifying value returned by radio button
  if it is selected when form is submitted

101
radio Object

• Event handlers
• onclick( )
• Invoked when radio button is clicked

102
radio Object

• HTML syntax
• ltinput
• type radio specifies this is radio button
• name name name to refer to this button
• value value value returned when button is
• selected
• checked button is initially checked
• onClick handler onclick( ) event handler
• gt

103
reset Object

• Notation
• form.name
• form.elementsj
• form.elementsname

104
reset Object

• Properties
• form
• Read-only reference to form object containing
  reset object
• name
• Read-only string specifying name of reset object
• type
• Read-only string specifying type of form element
• In this case, it is reset

105
reset Object

• Properties
• value
• Read-only string specifying text to appear in
  button

106
reset Object

• Event handlers
• onclick( )
• Invoked when reset button is clicked

107
reset Object

• HTML syntax
• ltinput
• type reset specifies this is reset button
• value label text to appear in button
• name name name to refer to this button
• onClick handler onclick( ) event handler
• gt

108
select Object

• Notation
• form.name
• form.elementsj
• form.elementsname

109
select Object

• Properties
• form
• Read-only reference to form object containing
  select object
• length
• Read-only integer specifying number of elements
  in the options array
• name
• Read-only string specifying name of select object

110
select Object

• Properties
• options
• An array of option objects, each of which
  describes one of the options displayed within the
  select object
• selectedIndex
• A read-only integer specifying the index of the
  selected option within the select object
• If the select object allows multiple selections,
  then this property only specifies the index of
  the first selected item or -1 if none are selected

111
select Object

• Properties
• type
• Read-only string specifying type of form element
• In this case, it is either select-one or
  select-multiple

112
select Object

• Event handlers
• onchange( )
• Invoked when the user selects or deselects an
  item
• onblur( )
• Invoked when a user action causes the select
  object to lose the keyboard focus
• onfocus( )
• Invoked when a user action causes the select
  object to gain the keyboard focus

113
select Object

• HTML syntax
• ltselect
• name name name identifying the
• object
• size integer number of visible options
• in object
• multiple multiple options may be
  selected
• onChange handler onchange( ) event
• handler
• onBlur handler onblur( ) event handler
• onFocus handler onfocus( ) event handler
• gt

114
options Object

• Notation
• select.optionsj

115
options Object

• Properties
• defaultSelected
• Read-only boolean value specifying whether this
  option object is selected by default
• index
• Read-only integer specifying index of this option
  object within the array of options
• selected
• Boolean value specifying whether this option
  object is currently selected

116
options Object

• Properties
• text
• Text that describes the option object
• value
• Specifies value to be passed to server if this
  option object is selected when form is submitted

117
options Object

• Constructor
• new Option(text, value,
• defaultSelected, selected)

118
options Object

• HTML syntax
• ltoption
• value value value returned when form
• submitted
• selected whether option is initially
• selected
• gt

119
submit Object

• Notation
• form.name
• form.elementsj
• form.elementsname

120
submit Object

• Properties
• form
• Read-only reference to form object containing
  submit object
• name
• Read-only string specifying name of submit object
• type
• Read-only string specifying type of form element
• In this case, it is submit

121
submit Object

• Properties
• value
• Read-only string specifying text to appear in
  button

122
submit Object

• Event handlers
• onclick( )
• Invoked when submit button is clicked

123
submit Object

• HTML syntax
• ltinput
• type submit specifies this is submit button
• value label text to appear in button
• name name name to refer to this button
• onClick handler onClick event handler
• gt

124
text Object

• Notation
• form.name
• form.elementsj
• form.elementsname

125
text Object

• Properties
• defaultValue
• Read-only string specifying initial value to
  appear in input field
• name
• Read-only string specifying name of text object
• type
• Read-only string specifying type of form element
• In this case, it is text

126
text Object

• Properties
• value
• String specifying value contained in input field

127
text Object

• Methods
• blur( )
• Remove keyboard focus from text object
• focus( )
• Set keyboard focus to text object
• When focus is set, all keystrokes are
  automatically entered into this object
• select( )
• Highlight all text in text object
• All future input will replace this highlighted
  text

128
text Object

• Event handlers
• onblur( )
• Invoked when a user action causes the text object
  to lose keyboard focus
• onchange( )
• Invoked when the user changes the value in the
  text object and move the keyboard focus elsewhere
• onfocus( )
• Invoked when a user action causes the text object
  to gain the keyboard focus

129
text Object

• HTML syntax
• ltinput
• type text specifies that this is a text object
• name name used to refer to this text
  object
• value default default value transmitted
  when
• form is submitted
• size integer number of characters in text
  object
• maxlength integer maximum allowed number of
  input
• characters
• onBlur handler onblur( ) event hander
• onChange handler onchange( ) event handler
• onFocus handler onfocus( ) event handler
• gt

130
textarea Object

• Notation
• form.name
• form.elementsj
• form.elementsname

131
textarea Object

• Properties
• defaultValue
• Read-only string specifying initial value to
  appear in input field
• name
• Read-only string specifying name of textarea
  object
• type
• Read-only string specifying type of form element
• In this case, it is textarea

132
textarea Object

• Properties
• value
• String specifying value contained in the textarea
  object

133
textarea Object

• Methods
• blur( )
• Remove keyboard focus from textarea object
• focus( )
• Set keyboard focus to textarea object
• When focus is set, all keystrokes are
  automatically entered into this object

134
textarea Object

• Event handlers
• onblur( )
• Invoked when a user action causes the textarea
  object to lose keyboard focus
• onchange( )
• Invoked when the user changes the value in the
  textarea object and move the keyboard focus
  elsewhere
• onfocus( )
• Invoked when a user action causes the textarea
  object to gain the keyboard focus

135
textarea Object

• HTML syntax
• lttextarea
• name name name of object
• rows integer number of lines of object
• columns integer character width of object
• wrap offvirtualphysical word wrapping
• onBlur handler onblur( ) event handler
• onChange handler onchange( ) event
• handler
• onFocus handler onfocus( ) event handler
• gt