A closer look at WebAssembly

Abstract: WebAssembly is a new emerging technology for the web which offers a low-level bytecode format for other languages to compile to. The aim of the technology is to effectively speed up the performance of the web, as well as to offer a way for developers to port existing libraries and code that were written in static languages such as C/C++ or Rust. The technology is currently supported in all the major browsers of today.This study takes a closer look at how the technology works and how it is compiled and executed across two of the major browsers as compared to JavaScript. Furthermore, a smaller experiment was conducted where AssemblyScript was used to compile to WebAssembly, with AssemblyScript being a typescript-to-WebAssembly compiler. The two technologies were then tested in terms of runtime performance and consistency across two browsers, operating systems as well as with different optimizations.The study showed that the technology goes through ahead-of-time-compilation and optimization through a compiler toolchain that depends on the language used as opposed to JavaScript which makes use of just-in-time-compilation. Furthermore, the fundamental structure for WebAssembly proved to be limited in order to be able to better link directly to machine code and through this offer performance benefits. The experiment conducted showed that WebAssembly performed better when it came to pure calculations but fell behind JavaScript when performing operations on an array. The reason is most likely due to the overhead of passing data structures between the two technologies. The experiment further showed that WebAssembly was able to offer a more consistent and predictable performance than JavaScript.