Overview
What
is JavaScript?
JavaScript
(JS) is an object-based programing language.
- JavaScript
is interpreted by the browser. JavaScript code is typically embedded
right in HTML pages
- JavaScript
programs are written using objects, which have properties, associated
data and behavior (methods) belonging to them
- JavaScript provides
various objects and methods or functions, and you can create new ones
Object-oriented
concepts
- Properties
are where the objects store their data, and are generally the
attributes that you get or set
- Methods
contain the various functions that can operate on an object
- Events are actions recognized by an object, such as a mouse moving
over it, or the user clicking on an object, such as a link
A
real world example:
- Consider
a speaker phone as an object
- Property:
speaker phone volume. telephone.speakerVolume=2
- Method:
dialing the telephone. telephone.dial("312-413-0003")
- Event:
the phone is ringing. ring(callerName)
What
else is JavaScript?
- JavaScript
is not Java
- JavaScript
is relatively easy to learn
- It
is a scripting language
- JavaScript
enables client-side processing
- JS
programs are built into the Web page in the form of a script
Versions
of JavaScript
- JavaScript
1.0 (Netscape 2.0)
- JavaScript
1.1 (Netscape 3.x, MSIE 4.x)
- JavaScript
1.2 (Netscape Communicator 4.0 to 4.04)
- JavaScript
1.3 (Netscape Comunicator 4.06 to 4.5)
- JavaScript 1.4 (Netscape Communicator 4.7.x and later)
- Microsoft
JScript ~ JavaScript 1.1
- WWW
Consortium standard: ECMA-262 JavaScript ~ JavaScript
1.1+
What
is JavaScript good for?
- Generating
on-the-fly Web pages or HTML
- Facilitating
user interaction with Web pages
- Adding
programming control to HTML
- Client-side
processing
- Validating
fields in HTML forms
- Detecting
browsers and browser environment
- Opening
and managing browser windows and frames
- Programming
navigation buttons
- Java and Plug-in
interface and control via LiveConnect
- Key
component of Dynamic HTML
- Dressing
up your Web pages
Alternatives
to JavaScript
- JScript,
Java, CGI scripts, VBScript, ActiveX controls
- Plug-ins
like Flash, Shockwave and others
- Other
scripting languages like PHP, Python and Lingo
JavaScript
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Modified: March 2, 2001 — Instructional Technology Lab
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