As3

AS3, short for ActionScript 3, is a programming language used primarily for applications that run on Adobe Flash Player and Adobe AIR. It was developed by Macromedia and later Adobe, and was released in 2006 as part of Flash Player 9. AS3 is a high-level, strongly typed, object-oriented language built on the ECMAScript standard, sharing many similarities with JavaScript but with a more rigid syntax and a robust class-based model.

Language features include class-based syntax, packages, namespaces, public/private/protected/internal access modifiers, interfaces, and inheritance. It supports strong typing, including optional dynamic typing with dynamic classes, and uses static typing with type annotations (for example, x:int). It provides a comprehensive standard library for the Flash APIs (display, events, networking, text), and supports EventDispatcher-based event handling, metadata, and E4X-style XML processing. It also includes native support for arrays, typed arrays, vector types, and a flexible signaling model.

Runtime and tooling: AS3 compiles to bytecode for AVM2, running inside either Adobe Flash Player or Adobe AIR. Code is typically organized into packages and compiled with tools such as Adobe Flex/Flash Builder, or the Flex Framework with MXML for building rich internet applications and desktop/mobile apps.

History and status: AS3 marked a major rewrite of ActionScript, emphasizing performance and scalability for richer web applications. With the decline of Flash and the end-of-life of Flash Player in 2020, AS3 usage has diminished, though it remains in legacy projects and in some educational contexts. Open-source efforts exist to transpile or port AS3 to JavaScript or to run-time environments.