16-04-2013, 02:42 PM
Action Script
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ABSTRACT
ActionScript is an object-oriented language originally developed by Macromedia Inc. (now owned by Adobe Systems). It is a dialect of ECMAScript (meaning it is a superset of the syntax and semantics of the language more widely known as JavaScript), and is used primarily for the development of websites and software targeting the Adobe Flash Player platform, used on Web pages in the form of embedded SWF files. The language itself is open-source in that its specification is offered free of charge and both an open source compiler (as part of Adobe Flex) and open source virtual machine (Mozilla Tamarin) are available.
ActionScript was initially designed for controlling simple 2D vector animations made in Adobe Flash (formerly Macromedia Flash). Initially focused on animation, early versions of Flash content offered few interactivity features and thus had very limited scripting capability. Later versions added functionality allowing for the creation of Web-based games and rich Internet applications with streaming media (such as video and audio). Today, ActionScript is suitable for use in some database applications, and in basic robotics, as with the Make Controller Kit.
Flash MX 2004 introduced ActionScript 2.0, a scripting programming language more suited to the development of Flash applications. It is often possible to save time by scripting something rather than animating it, which usually also enables a higher level of flexibility when editing.
Since the arrival of the Flash Player 9 alpha (in 2006) a newer version of ActionScript has been released, ActionScript 3.0. ActionScript 3.0 is an object-oriented programming language allowing far more control and code reusability when building complex Flash applications. This version of the language is intended to be compiled and run on a version of the ActionScript Virtual Machine that has been itself completely re-written from the ground up (dubbed AVM2).[2] Because of this, code written in ActionScript 3.0 is generally targeted for Flash Player 9 and higher and will not work in previous versions. At the same time, ActionScript 3.0 executes up to 10 times faster than legacy ActionScript code.[3]
History
Action Script started as an object-oriented language for Macromedia's Flash authoring tool, now developed by Adobe Systems as Adobe Flash. The first three versions of the Flash authoring tool provided limited interactivity features. Early Flash developers could attach a simple command, called an "action", to a button or a frame. The set of actions was basic navigation controls, with commands such as "play", "stop", "getURL", and "gotoAndPlay".
With the release of Flash 4 in 1999, this simple set of actions became a small scripting language. New capabilities introduced for Flash 4 included variables, expressions, operators, if statements, and loops. Although referred to internally as "ActionScript", the Flash 4 user manual and marketing documents continued to use the term "actions" to describe this set of commands.
Timeline by ActionScript version
2000–2004: ActionScript "1.0" With the release of Flash 5 in September 2000, the "actions" from Flash 4 were enhanced once more and named "ActionScript" for the first time.[6] This was the first version of ActionScript with influences from JavaScript and the ECMA-262 (Third Edition) standard, supporting the said standard's object model and many of its core data types. Local variables may be declared with the var statement, and user-defined functions with parameter passing and return values can also be created. Notably, ActionScript could now also be typed with a text editor rather than being assembled by choosing actions from drop-down lists and dialog box controls. With the next release of its authoring tool, Flash MX, and its corresponding player, Flash Player 6, the language remained essentially unchanged; there were only minor changes, such as the addition of the switch statement and the "strict equality" (===) operator, which brought it closer to being ECMA-262-compliant. Two important features of ActionScript that distinguish it from later versions are its loose type system and its reliance on prototype-based inheritance. Loose typing refers to the ability of a variable to hold any type of data. This allows for rapid script development and is particularly well-suited for small-scale scripting projects. Prototype-based inheritance is the ActionScript 1.0 mechanism for code reuse and object-oriented programming. Instead of a class keyword that defines common characteristics of a class, ActionScript 1.0 uses a special object that serves as a "prototype" for a class of objects. All common characteristics of a class are defined in the class's prototype object and every instance of that class contains a link to that prototype object
AIR
Adobe AIR supports ActionScript, in addition to some extended contents, such as the Stage3D engine Adobe has developed. ActionScript on Adobe AIR has also increased efficiency and popularity because of its versatility of being able to run on many interfaces. The amount of APIs (Application programming interfaces) pointed at ActionScript 3.0 has also risen dramatically