Introduction to JavaScript

What is JavaScript?

JavaScript is an object-based scripting language for web client and server applications.
Client-Side vs. Server-Side JavaScript
- the same core language
- different pre-defined objects and functions in web browser/server.

Advantages of Using JavaScript (Client-Side)

Validate user's input.
Perform aggregrate calculations.
Easily prompt a user for confirmation, alert, pop-up information.
Easy and powerful control of Web browser's behaviors and HTML page component's properties.
Conditionalize HTML.
Perform other opeations in the client, independent of server information.
Control of Dynamic HTML.

Advantages of Using JavaScript (Server-Side)

Maintain information through a series of client access.
Maintain data shared among several clients or applications.
Access databases/files on the server
Call external objects, or libraries on the server.
Generate HTML output dynamically.

JavaScript on Web Browser

<html>
<head><title>JavaScript in Browser</title></head>
<body>
<script language="JavaScript">
var titleNo=2;
document.write("<h1>Document No"+titleNo+" </h1>\n");
</script>
</body>
</html>

JavaScript on Web Server

Netscape Enterprise Server:
<server>
...
</server>
ASP (Microsoft IIS, PWS):
<%@ LANGUAGE = JScript %>
<% ... %>