What is WebAssembly?

WebAssembly is not a high-level programming language like JavaScript, but a compiled binary format that all major browsers are currently able to execute. WebAssembly is a kind of machine bytecode that was not designed to run directly on any real machine hardware, but runs in the JavaScript engine built into every browser. In some ways, it is similar to the old Java Virtual Machine (JVM); for example, it is a platform-independent compiled bytecode. One major problem with JavaScript bytecode is its requirement for a plugin to be downloaded and installed in the browser for the bytecode to run. Not only is WebAssembly designed to be run directly in a browser without a plugin, but it is also intended to produce a compact binary format that executes efficiently inside a web browser. The MVP version of the specification leverages existing work by the browser makers designing their JavaScript just-in-time (JIT) compiler. WebAssembly is currently a young technology and many improvements are planned. However, developers using the current version of WebAssembly have already seen performance improvements over JavaScript of 10–800%.