wasmrt

Compile nim to wasm

import wasmrt
proc consoleLog(a: string) {.importwasmraw: "console.log($0)".}
consoleLog("Hello, world!")

nim c --out:test.wasm test.nim # Special nim config is required, see below
node tests/runwasm.js test.wasm

Prerequisites

• clang 20.0 or later
• Special Nim config, like this one
• [Optional] wasm-opt - a tool to compact your wasm file

Run your wasm

The wasm file generated this way is pretty standalone, and requires only the following JavaScript code to bootstrap:

function runNimWasm(w){for(i of WebAssembly.Module.exports(w))n=i.name,n[0]==';'&&new Function('m',n)(w)}

runNimWasm takes the output of WebAssembly.compile function. E.g. to run a wasm file in nodejs, use smth like runwasm.js

Convert wasm to html

The generated wasm file can be "converted" to a standalone html file with wasm2html tool provided in this package.

nim c --out:test.wasm test.nim # Special nim config is required, see below
wasm2html test.wasm test.html

Why no Emscripten?

The goal of this project is to produce self-contained standalone wasm files from nim code, without any JS glue, or "desktop platform emulation".