Module Registration

Module registration is done at compile time. The root argument must be a struct type, usually @This() from the addon root file.

`NODE_API_MODULE`

napi.NODE_API_MODULE(comptime name: []const u8, comptime root: type) void

Exports every public field and declaration on root into the JavaScript module export object.

const napi = @import("napi");

pub const version = "0.1.0";

pub fn add(left: i32, right: i32) i32 {
    return left + right;
}

comptime {
    napi.NODE_API_MODULE("hello", @This());
}

The resulting JavaScript module has version and add exports.

`NODE_API_MODULE_WITH_INIT`

napi.NODE_API_MODULE_WITH_INIT(
    comptime name: []const u8,
    comptime root: type,
    init: ?fn (env: napi.Env, exports: napi.Object) anyerror!?napi.Object,
) void

Use this form when the module needs custom setup after generated exports are attached.

fn init(env: napi.Env, exports: napi.Object) !?napi.Object {
    try exports.Set("loadedAt", env.createDate(0));
    return null;
}

comptime {
    napi.NODE_API_MODULE_WITH_INIT("hello", @This(), init);
}

Returning null keeps the generated export object. Returning an object replaces it.

Export Rules

Root member	Export behavior
`pub fn` declaration	Converted into a JavaScript function.
`pub const` declaration	Converted through the `Napi.to_napi_value` conversion layer.
public struct field on the root type	Converted and attached as an export.
`pub const` class wrapper	Exported as a JavaScript class constructor.
`pub const` enum type	Exported as a TypeScript enum during declaration generation.
`pub const napi_allocator`	Reserved for allocator configuration and not exported.

If conversion fails during module initialization, the wrapper throws the pending JavaScript error into the current Env.

Init Hook

The init hook runs after generated exports are attached.

fn init(env: napi.Env, exports: napi.Object) !?napi.Object {
    try exports.Set("global", try env.getGlobal());
    return null;
}

Return null to keep the generated export object. Return another napi.Object to replace module.exports.

Type Generation Mode

When build_options.napi_tsgen is enabled by generateTypeDefinition, registration becomes a no-op at runtime. This lets the generator compile the addon root for reflection without emitting a native module initializer.

napi.dts and napi.Dts also switch behavior in this mode, so custom TypeScript text affects declarations without changing runtime exports.