Node addon internal require

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Node-API addons that obtain Node's internal requireBuiltin() without starting Node with --expose-internals.

These are not pure public Node-API implementations. Each addon is loaded through a stable N-API v9 entry point, but the useful work probes private Node/V8 runtime state and validates the result at runtime. If a runtime does not match the expected invariants, the addon must fail closed instead of guessing offsets.

Install

npm install node-addon-internal-loader
# or
npm install node-addon-require-builtin

Published packages use two product families plus one shared loader package:

node-addon-native-custom-loader
node-addon-require-builtin
node-addon-require-builtin-darwin-arm64
node-addon-require-builtin-darwin-x64
node-addon-require-builtin-linux-arm64-gnu
node-addon-require-builtin-linux-arm64-musl
node-addon-require-builtin-linux-x64-gnu
node-addon-require-builtin-linux-x64-musl
node-addon-require-builtin-win32-arm64-msvc
node-addon-require-builtin-win32-ia32-msvc
node-addon-require-builtin-win32-x64-msvc
node-addon-internal-loader
node-addon-internal-loader-darwin-arm64
node-addon-internal-loader-darwin-x64
node-addon-internal-loader-linux-arm64-gnu
node-addon-internal-loader-linux-arm64-musl
node-addon-internal-loader-linux-x64-gnu
node-addon-internal-loader-linux-x64-musl
node-addon-internal-loader-win32-arm64-msvc
node-addon-internal-loader-win32-ia32-msvc
node-addon-internal-loader-win32-x64-msvc

Each entry package requires a CI-validated current-platform optional package. If no compatible optional prebuild is available, installation fails closed instead of compiling an unvalidated local binary.

Usage

Use node-addon-internal-loader when only the CommonJS and ESM loader internals are needed:

const internalLoader = require('node-addon-internal-loader');

const esmLoader = internalLoader.requireBuiltin('internal/modules/esm/loader');
const cascadedLoader = esmLoader.getOrInitializeCascadedLoader();

Use node-addon-require-builtin when unrestricted internal builtin loading is required:

const requireBuiltinAddon = require('node-addon-require-builtin');

const realm = requireBuiltinAddon.requireBuiltin('internal/bootstrap/realm');

Both entry packages expose the same small API:

• requireBuiltin(moduleId): returns the selected internal module.
• isAllowedInternalId(moduleId): returns whether moduleId is loadable.
• getBindingInfo(): lazily returns binding diagnostics such as mode, product, backend, abi, bindingSource, and bindingPath.

node-addon-internal-loader only allows internal/modules/cjs/loader and internal/modules/esm/loader; the allowlist is enforced in the native addon before calling Node's internal requireBuiltin(). node-addon-require-builtin does not restrict module ids: isAllowedInternalId() always returns true, and requireBuiltin(id) forwards any string id to Node. See docs/internal-modules.md for the allowlist and supported Node version ranges.

Treat returned internal modules as unstable Node implementation details. These packages do not make Node internals public API.

Backends

The native implementation has one product dimension and one backend dimension:

Products:

• internal-loader: default product. It enforces the CJS/ESM loader allowlist.
• require-builtin: unrestricted product. It forwards any string id to Node's builtin require.

Backends:

• napi: default release backend. It builds one napi-v9 binary per supported platform/arch and discovers private Node/V8 state at runtime.
• nodeabi: Node-major/ABI backend used for source-build validation in this repository. It is not published as an optional prebuild artifact.

The published loader defaults to auto, which resolves to the current platform's napi-v9 optional prebuild. Set NARB_BACKEND=napi to force that backend. Source builds and product-specific tests use NARB_PRODUCT=internal-loader or NARB_PRODUCT=require-builtin.

Development

corepack enable
pnpm install
pnpm build
pnpm test

pnpm build builds TypeScript entrypoints and the N-API native addon into packages/internal-loader/entry/build/ by default. Set NARB_PRODUCT=require-builtin to build the unrestricted product into packages/require-builtin/entry/build/. Source builds are a repository development and CI workflow only; published packages do not include native sources for install-time fallback builds.

For backend comparison with official Node.js public headers:

eval "$(pnpm -s headers -- --version 24.18.0)"
pnpm test:backends

For current-platform prebuild preparation:

eval "$(pnpm -s headers -- --version 24.18.0)"
pnpm build:prebuild:napi
pnpm test:optional

See docs/development.md for the full local workflow, docs/architecture.md for the runtime design, and docs/packaging.md for the optional package model.

Support Status

The supported optional prebuild target set is intentionally conservative:

Platform	Node 20	Node 22	Node 24	Node 26
macOS arm64 (darwin-arm64)	Supported	Supported	Supported	Supported
macOS x64 (darwin-x64)	Supported	Supported	Supported	Supported
Linux glibc arm64 (linux-arm64-gnu)	Supported	Supported	Supported	Supported
Linux glibc x64 (linux-x64-gnu)	Supported	Supported	Supported	Supported
Linux musl arm64 (linux-arm64-musl)	Supported	Supported	Supported	Supported
Linux musl x64 (linux-x64-musl)	Supported	Supported	Supported	Supported
Windows arm64 MSVC (win32-arm64-msvc)	Supported	Supported	Supported	Supported
Windows x86 MSVC (win32-ia32-msvc)	Supported	Supported	No 32-bit runtime	No 32-bit runtime
Windows x64 MSVC (win32-x64-msvc)	Supported	Supported	Supported	Supported

Both product families publish one napi-v9 binary per supported platform, tested across Node 20, 22, 24, and 26. Linux GNU prebuilds require glibc 2.28 or newer and a GLIBCXX_3.4.25-compatible C++ runtime. Linux musl prebuilds are built and tested on Alpine 3.23, including npm installs on musl Node 20/22/24/26. Node.js stopped shipping 32-bit Windows binaries after v22, so win32-ia32-msvc covers only Node 20 and 22.

Electron 43.0.0, 44.0.0, 44.7.0, and 45.0.0-alpha.6 are also tested in real main processes for both products. The Electron matrix covers macOS arm64/x64, Linux glibc arm64/x64, and Windows arm64/x64. Electron 43 additionally covers Windows ia32; later releases do not publish an ia32 binary. Other Electron versions fail closed until they are analyzed and added explicitly. See docs/support-matrix.md and docs/internal-modules.md.

License

MIT