what is java script?

Question

whhy do i need it

Answer 1

It is a scripting language embedded in web pages that execute instructions for custom code.

You don't NEED it, but it is a tool available for web programming.
JavaScript is the name of Netscape Communications Corporation's and now the Mozilla Foundation's implementation of the ECMAScript standard, a scripting language based on the concept of prototype-based programming. The language is best known for its use in websites (as client-side JavaScript), but is also used to enable scripting access to objects embedded in other applications.

Despite the name, JavaScript is only distantly related to the Java programming language, the main similarity being their common debt to the C syntax. Semantically, JavaScript syntax has far more in common with the Self programming language.

One major use of web-based JavaScript is to write functions that are embedded in or included from HTML pages and interact with the Document Object Model (DOM) of the page to perform tasks not possible in HTML alone. Some common examples of this usage follow.

Opening or popping up a new window with programmatic control over the size, position and 'look' of the new window (i.e. whether or not the menus, toolbars etc are visible).
validation of web form input values to make sure that they will be accepted before they are submitted to the server.
Changing images as the mouse cursor moves over them: This effect is often used to draw the user's attention to important links displayed as graphical elements.
The DOM interfaces in various browsers differ and don't always match the W3C DOM standards. Rather than write different variants of a JavaScript function for each of the many browsers in common use today, it is usually possible, by carefully following the W3C DOM Level 1 or 2 standards, to provide the required functionality in a standards-compliant way that most browsers will execute correctly. Care must always be taken to ensure that the web page degrades gracefully and so is still usable by any user who:

has JavaScript execution disabled - for example as a security precaution
has a browser that does not understand the JavaScript - for example on a PDA or mobile phone
is visually or otherwise disabled and may be using an unusual browser, a speech browser or may have selected extreme text magnification. For more information on this, see the Web Accessibility Initiative
Other examples of JavaScript interacting with a web page's DOM have been called DHTML and SPA.

A different example of the use of JavaScript in web pages is to make calls to web and web-service servers after the page has loaded, depending upon user actions. These calls can obtain new information, which further JavaScript can merge with the existing page's DOM so that it is displayed. This is the basis of Ajax programming. PnP JavaScript design pattern was adopted gradually after commonly use of Ajax to reduce JavaScript maintenance cost.

Outside of the Web, JavaScript interpreters are embedded in a number of tools. Adobe Acrobat and Adobe Reader support JavaScript in PDF files. The Mozilla platform, which underlies several common web browsers, uses JavaScript to implement the user interface and transaction logic of its various products. JavaScript interpreters are also embedded in proprietary applications that lack scriptable interfaces. Dashboard Widgets in Apple's Mac OS X v10.4 are implemented using JavaScript. Microsoft's Active Scripting technology supports JavaScript-compatible JScript as an operating system scripting language. JScript .NET is a CLI-compliant language that is similar to JScript, but has further object oriented programming features. Tools in the Adobe Creative Suite, including Photoshop, allow scripting through JavaScript

Answer 2

It is a scripting language used by almost all interactive websites, without it a webpage is as static as a printed page would have been if we were to scan a paper page and put on screen..

It was created by Netscape as LiveScript; but it shares similar syntax ancestry as Java and C# also it coincided the introduction of Java so it is renamed JavaScript.

It is standardized; the formal name is ECMAScript as opposed to the less used scripting of MS VBScript. But the web supplement of DOM modelling is not completely standardized, the rebranded version of JavaScript is MS JScript; adopted to use on many things in parallel to VBScript.

Answer 3

Javascript is a client-side scripting language used for internet programming. Now-adays the majority of websites that are not static websites (like a singular page) use some sort of javascript.

When images change while you watch it, when forms 'hide and show' various sections that's all (usually) powered by javascript. A lot of the interactive stuff used on websites are run by javascript. Unfortunately, pop-up ads are also run by javascript

If you turn javascript off in your browser these sites might not work right. True pop-ups are annoying but you lose the functionality of sites and the usability of them if you turn them off. If you're learning how to build websites... it's also a handy tool that'll make your life a lot easier.

To get started learning javascript I recommend sites like www.echoecho.com to learn with.

Answer 4

There is nothing like user scripts... Java script is a client side programming language for web.

Answer 5

http://en.wikipedia.org/wiki/Java_script