JavaScript

JavaScript is what is known as a client-side scripting language that provides powerful extensions to the HyperText Markup Language (HTML) used to write web pages. JavaScript is an interpreted language, which means that it is not compiled into a separate executable program but instead the JavaScript code is embedded within the HTML document. It is downloaded with the HTML document and translated by the client machine when the page is loaded into the web browser.

A misconception held by many people is that JavaScript is a cut-down version of the Java programming language. Although they share many similarities in language syntax, and JavaScript is also object-based, they are not the same thing at all. JavaScript is much simpler and is designed to run only within the browser, whereas Java can be used to produce stand­alone applications. JavaScript was written with the intention of being used by web developers with little or no experience of object-oriented programming, and the emphasis was on providing the means to add dynamic functionality to web pages in as easy a way as possible.

JavaScript is an interpreted programming language whose interpreter is embedded inside Web browser software, such as Microsoft Internet Explorer and Netscape Navigator. This means that script contained in Web documents can be read by the browser's JavaScript engine whenever the document is loaded into the browser window. In this way, Web documents can be made to respond to the user's actions and to perform dynamic visual effects. JavaScript should not be confused with the compiled programming language called Java from Sun Microsystems which, although bearing some resemblance, is a completely different language. JavaScript appeared in December 1995 and was initially called LiveScript, although the name was soon changed for marketing reasons. The JavaScript language contains many impressive features but for security reasons it cannot read or write files, with the exception of cookie files that store a small amount of data. It is important to learn the basics - so the mechanics of the language are covered first in chapters that explain, by example, how to write JavaScript programs. Then the browser Document Object Model (DOM) is introduced to illustrate how all Web pages contain objects with properties that can be manipulated by JavaScript. Combining JavaScript with knowledge of the DOM allows the creation of powerful Dynamic HTML (DHTML) effects.

Questionnaire:

• What is Java Script? Explain.