Javascript

= Javascript = toc Javascript is a lightweight programming language designed for the web. It is used to add interactivity to web pages. Javascript runs on the client side – this means that it uses website visitors' processing power and that things seem to happen instantly in their browser. Javascript allows users to interact with a website without the necessity of accessing the server and re-downloading the page every time they do something. See also Javascript Animations.

A micro-history
Javascript was originally developed for Netscape in the mid-nineties. Microsoft soon developed a competing scripting language. The introduction of the Document Object Model (DOM) helped to standardize scripting. The DOM also allowed for much richer interaction with web pages. Javascript has since become the standard scripting language supported by all browsers.

What can Javascript do?
Traditional uses of Javascript include the functionality and validation of forms, and various alerts and prompts. Javascript can change, add to, or manipulate anything about a web page, however, it cannot interact with external files and databases.

Some common contemporary uses of Javascript include:
 * Auto-complete text fields
 * Instant feedback if a phone number is incorrectly formatted or a username is already taken
 * Automatically updating content without reloading a page, as in stock market tickers
 * Drop-down menus and links that expand content with additional details
 * Animated elements such as highlighting sections of a page or showing and hiding information

Security Concerns
Some people think that Javascript has too much power to manipulate files on their hard drive and so have their browsers disable it. Although such cases are increasingly in the minority, essential functions of a site, such as navigation, should still be able to be accessed without Javascript.