wvwasi

A WebView with WebAssembly System Interface (WASI) may be the best Javascript/WebAssembly runtime, and wvwasi is it.

                              |
Javascript/WebAssembly code   |  Javascript/WebAssembly application code
                              |                 |
                              |                 v
                              | WASI syscalls (inserted by compiler toolchain)
                              |                 |
------------------------------+                 |
                              |                 v
Javascript/WebAssembly runtime|    wvwasi (implementation WASI in webview)
(WebView)                     |                 |
                              |                 v
                              |        platform-specific calls
                              |

(Hence wvwasi isn't for making programs execute on WASI runtimes. That would either be a wasm32-wasi target complied by rust, or done through POSIX emulation by the Emscripten or wasi-sdk toolchains.)