02-cpp-node-addon-api

02 — C++ with node-addon-api

The same shape as example 1, in C++.

_ = try czb.addNodeAddon(b, .{
    .name = "matrix_addon",
    .cpp_std = "c++20",
});

Two things happen without being asked for:

• libc++ is linked, because C++ sources were found. .link_libcpp exists if you need to override that; you normally do not.
• node-addon-api's headers are added. A copy ships with c-cpp-zig-build, so this would compile with no dependencies at all. This example declares its own anyway, which is the better habit: a declared version wins over the bundled one, and napi.h does change between majors.

npm install       # node-addon-api
npm run build
node --test

npx c-cpp-zig-build info   # says which copy of the headers was used

Worth noticing

C++ exceptions must not escape into JavaScript. Matrix::multiply throws std::invalid_argument on mismatched shapes; the binding catches it and rethrows it as a Napi::Error. Letting it through takes the process down. The test asserts the JavaScript side sees a normal Error.

try {
  return ToJs(env, a.multiply(b));
} catch (const std::invalid_argument& error) {
  throw Napi::Error::New(env, error.what());
}

node-addon-api throws C++ exceptions to signal JavaScript ones. That is why .exceptions is left on. If you turn it off, the wrapper switches to returning Maybe values and every call site has to check — set .exceptions = false and the two macros that requires are defined for you.