From bytecode to JavaScript: the Js_of_ocaml compiler

We present the design and implementation of a compiler from OCaml bytecode to JavaScript. The compiler first translate the bytecode into an SSA intermediate representation on which optimizations are performed, before generating JavaScript. We believe that taking bytecode as input instead of a high-level language is a sensible choice. Virtual machines provide a very stable API. Such a compiler is thus easy to maintain. It is also convenient to use: it can just be added to an existing installation of the development tools. Already compiled libraries can be used directly, with no need to reinstall anything. Finally, some virtual machines are the target of several languages. A bytecode to JavaScript compiler would make it possible to retarget all these languages to Web browsers at once. Copyright c © 0000 John Wiley & Sons, Ltd.