vite-plugin-cpp-loader

Import .cpp files directly into TypeScript. Functions are automagically compiled to WebAssembly via Emscripten and callable with full type safety — no boilerplate, no manual em++ invocations.

Prerequisites

Emscripten must be installed and em++ available in your PATH.

macOS:

brew install emscripten

Linux / macOS (via emsdk):

git clone https://github.com/emscripten-core/emsdk.git
cd emsdk && ./emsdk install latest && ./emsdk activate latest
source ./emsdk_env.sh

Windows:

git clone https://github.com/emscripten-core/emsdk.git
cd emsdk && emsdk install latest && emsdk activate latest && emsdk_env.bat

Installation

npm install vite-plugin-cpp-loader --save-dev

Setup

// vite.config.ts
import { defineConfig } from 'vite';
import cppLoader from 'vite-plugin-cpp-loader';

export default defineConfig({
  plugins: [cppLoader()]
});

Usage

Write plain C++ — no Emscripten boilerplate required. All top-level non-static functions are automatically exported.

math.cpp

int add(int a, int b) {
    return a + b;
}

main.ts

import { add } from './math.cpp';

add(2, 3); // 5

If you only want to export a subset of functions, mark the ones you want to keep internal as static and they will be excluded.

Type safety

Types are inferred from your C++ signatures:

import { add } from './math.cpp';

add(2, 3);     // ✅
add("2", 3);   // ❌ Argument of type 'string' is not assignable to parameter of type 'number'

Supported C++ → TypeScript mappings:

C++	TypeScript
int, float, double, long, short, unsigned	number
int32_t, uint32_t, int64_t, uint64_t, size_t	number
bool	boolean
std::string, const char*	string
void	void
emscripten::val	any

Complex types (STL containers, custom classes) are not supported as parameters or return types.

Options

cppLoader({
  emccArgs: ['-sASSERTIONS=1'],   // extra flags passed to em++
  optimizationLevel: 'O3',         // default: 'O2'
  cacheDir: '.my-wasm-cache',      // default: 'node_modules/.cpp-wasm'
  setupVSCode: false,              // disable auto-generation of .vscode/c_cpp_properties.json
})

How it works

1. Vite intercepts any import of a .cpp file.
2. The plugin invokes em++ (Emscripten) to compile the C++ to a .wasm binary + a JS glue module.
3. Function bindings are generated automatically using Embind — no raw pointers or manual memory management.
4. TypeScript declarations are inferred from the C++ signatures so your editor gets full autocompletion.

The compiled .wasm is cached in node_modules/.cpp-wasm so rebuilds are near-instant when the source hasn't changed.

Troubleshooting

em++ not found — make sure Emscripten is installed and in your PATH. If you installed via emsdk, run source ./emsdk_env.sh before starting the dev server.

License

MIT