COMP284 Scripting Languages Handouts (8 on 1)
COMP284 Scripting Languages
Lecture 17: JavaScript (Part 4)
Handouts (8 on 1)
Ullrich Hustadt
Department of Computer Science
School of Electrical Engineering, Electronics, and Computer Science
University of Liverpool
Contents
1 Dynamic web pages using JavaScript
Window and Document objects
Window object: Properties and methods
Dialog boxes
Input validation
Document object and Document Object Model
2 Event-driven Programs
Introduction
Events
COMP284 Scripting Languages Lecture 17 Slide L17 1
Dynamic web pages using JavaScript Window and Document objects
Window and Document objects
JavaScript provides two objects that are essential to the creation of
dynamic web pages and interactive web applications:
window object
a JavaScript object that represents a browser window or tab
automatically created whith every instance of a
allows properties of a window to be accessed and manipulated
; JavaScript provides methods that allow window objects to be
created and manipulated
Example: window.open(http://www.csc.liv.ac.uk,Home)
whenever an object method or property is referenced in a script without
an object name and dot prefix it is assumed by JavaScript to be a
member of the window object
Example: We can write alert() instead of window.alert()
COMP284 Scripting Languages Lecture 17 Slide L17 2
Dynamic web pages using JavaScript Window object: Properties and methods
Window object
A window object represents an open window in a browser.
If a document contain frames, then there is
one window object, window, for the HTML document
and one additional window object for each frame,
accessible via an array window.frames
A window object has properties including
document document object for the window
history history object for the window
location location object (current URL) for the window
navigator navigator (web browser) object for the window
opener reference to the window that created the window
innerHeight inner height of a windows content area
innerWidth inner width of a windows content area
closed boolean value indicating whether the window is
(still) open
COMP284 Scripting Languages Lecture 17 Slide L17 3
Dynamic web pages using JavaScript Window object: Properties and methods
Navigator object
Properties of a navigator object include
navigator.appName the web browers name
navigator.appVersion the web browers version
Example: Load different style sheets depending on browser
COMP284 Scripting Languages Lecture 17 Slide L17 4
Dynamic web pages using JavaScript Window object: Properties and methods
Window object
Methods provided by a window object include
open(url, name [, features])
opens a new browser window/tab
returns a reference to a window object
url is the URL to access in the new window; can be the empty string
name is a name given to the window for later reference
features is a string that determines various window features
The standard sequence for the creation of a new windows is not:
// new instance of Window class
var newWin = new Window ()
newWin.document.write( )
instead it is
// new window created by using open with an existing one
var newWin = window.open ()
newWin.document.write( )
COMP284 Scripting Languages Lecture 17 Slide L17 5
Dynamic web pages using JavaScript Window object: Properties and methods
Window object
Methods provided by a window object include
close()
closes a browser window/tab
focus()
give focus to a window (bring the window to the front)
blur()
removes focus from a window (moves the window behind others)
print()
prints (sends to a printer) the contents of the current window
COMP284 Scripting Languages Lecture 17 Slide L17 6
Dynamic web pages using JavaScript Window object: Properties and methods
Window object: Example
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