AssemblyScript

AssemblyScript is a TypeScript-like language designed to compile to WebAssembly. It enables developers to write code in a familiar TypeScript syntax while targeting the WebAssembly runtime, allowing compute-intensive tasks to run with near-native performance in web browsers and other environments that support WebAssembly. AssemblyScript maintains a statically typed subset of TypeScript, with explicit types for numbers (i32, i64, f32, f64), arrays, classes, and interfaces, and it focuses on producing predictable, efficient WebAssembly code by avoiding most dynamic JavaScript features.

The compiler, known as asc, translates AssemblyScript source into a WebAssembly module (.wasm) and a small JavaScript glue layer that loads the module and binds its exports to the host environment. The standard library (assemblyscript/std) provides basic data structures and utilities used by common programs. WebAssembly modules generated by AssemblyScript access memory through a linear memory object and can be used from JavaScript or Node.js via the WebAssembly API, with the option to import host functions for additional interoperability.

Typical use cases include performance-critical components such as image processing, simulations, cryptography, and data processing that run alongside existing JavaScript code. While offering speed advantages, AssemblyScript imposes constraints on memory management and interoperability compared to plain JavaScript, and developers may need to manage memory explicitly in performance-critical scenarios.

The project is open source and community driven, with ongoing work to expand type coverage, tooling, debugging, and integration with build systems. It remains a choice for developers who want to leverage TypeScript familiarity to write high-performance WebAssembly modules.