Screen output and keyboard input

MODULE IV

• Introduction to JavaScript and jQuery - The Basics of JavaScript: Overview of JavaScript, Object Orientation and

• Originally developed by Netscape
• JavaScript was invented by Brendan Eich in 1995
• Joint Development with Sun Microsystems in 1995
• can be run on any operating systems and almost all web browsers.

• ECMA-262 edition 3 is the current standard
– Edition 4 is under development
• Supported by Netscape, Mozilla, Internet Explorer

• Used to create cookies.

JavaScript Components

Similarity between java & JavaScript• Syntax of their expressions , assignment statements & control statements

• The main task of most JavaScript programs is to respond to events

• For example, a JavaScript program could validate data in a form before it is submitted to a server

– JavaScript in the body element will be executed once as the page is loaded

Object Orientation and JavaScript

• Root object in JavaScript is Object
• The Object object is the ancestor of all
objects in a JavaScript program
– Object has no data properties, but several method properties

JavaScript in XHTML

• Must begin with a letter, an underscore or a dollar sign

• No length limitations for identifiers

,the rest of the line is considered as comment 2. /*…………………*/ (single & multiple line
comments)

– Simply ignore the contents of the script element & cause no problems.

• Old browsers does not recognize the script tag, simply read as text

• This, however does not work, at least in Firefox:

<script type=“text/javascript”>

• The problem seems to be that the CDATA tag causes an internal JavaScript error

JavaScript in XHTML: CDATA (2)