| Platform independent|
| Imperative, Unstructured, Expression-oriented|
WebAssembly or wasm is an experimental efficient low-level bytecode format for in-browser client-side scripting, which is currently in development. Its initial aim is to support compilation from C and C++, though other source languages such as Rust are also supported.
WebAssembly was first announced on 17 June 2015 and on 15 March 2016 was demonstrated executing Unity's Angry Bots in Firefox, Chromium, Google Chrome, and Microsoft Edge.
The initial implementation of WebAssembly support in browsers will be based on asm.js and PNaCl. After the minimum viable product (MVP) release, there are plans to support garbage collection which would make WebAssembly a compilation target for garbage collected programming languages like Java and C#. The team working on WebAssembly includes people from Mozilla, Microsoft, Google and Apple.
It defines a WebAssembly binary format, which is not designed to be used by humans, as well as a human-readable "Linear Assembly Bytecode" format that resembles traditional assembly languages.
The table below represents 3 different views of the same source code input from the left, as it is converted to a wasm intermediate format, then to wasm binary.
Internally at the moment the tooling of the wasm compiler system uses s-expressions (for parsing simplicity as well as extra information that "linear assembly bytecode" representation does not contain) to handle intermediate code. An example is shown below: