About Node.js native code compilation concepts, compatibility and terms; Node.js Open Source vs 1990s/early 2000s Windows/Linux Dev

In a recent post of mine: Notes on sharing React Native project code between my Win 11 desktop PC and old Win 10 mini Laptop, for the backend API and so not related to React Native, I have described how I encountered a Node.js version incompatiblity error for the package better-sqlite3, https://www.npmjs.com/package/better-sqlite3 . The error was that the package was compiled against a different Node.js version using NODE_MODULE_VERSION 115 but was being attempted to be loaded/run on Node.js version that requires NODE_MODULE_VERSION 127. better-sqlite3 uses a compiled binary. I got an understanding about such compiled binary and NODE_MODULE_VERSION compatibility related stuff through a chat with ChatGPT on 5 Jun. 2025. That got extended to Node.js Open Source vs 1990 to 2002 Windows/Linux related development world. Given below are notes based on that chat. The chat itself is shared publicly: https://chatgpt.com/share/6842bd51-2390-8013-9c7e-ff927680738a .

better-sqlite3 package

✅ Key Points:

C++ Native Code:
- The package does include C++ source code, such as src/better_sqlite3.cpp.
- It uses Node.js native addons, which means it needs to be compiled into a binary that Node can load.
binding.gyp File:
- The presence of binding.gyp confirms that it uses node-gyp to build a native addon (a .node file, not .so).
- This defines how the C++ code is compiled for the current platform.
Compiled Binary Output:

During the npm install process, either:
- A prebuilt binary is downloaded (from GitHub Releases or a CDN) if available for your platform and Node version.
- Or, the addon is built locally using node-gyp and a C++ compiler if no prebuilt binary matches.
The compiled output is typically a .node file (e.g., better_sqlite3.node) in the build/Release/ directory.
My project (Simon Grimm tutorial lms-api app) did have better_sqlite3.node in node_modules/better-sqlite3/build/Release/ folder.

✅ What is a `.node` file?

A .node file is a native addon for Node.js. It is:

A compiled binary (just like a .dll on Windows or .so on Linux).
Contains C/C++ compiled code, built specifically to interface with Node.js via the V8 engine and Node's C++ APIs.
Loaded directly by Node.js using require() — similar to a JavaScript module, but implemented in native code.

🔧 In your case (`better-sqlite3.node`):

This file contains the compiled C++ code from the better-sqlite3 source (src/better_sqlite3.cpp).
It wraps around the SQLite C library, exposing a fast, synchronous SQLite interface to Node.js.
When your JS code does something like:
```
const Database = require('better-sqlite3');
```
Node.js actually loads this .node file, not a .js file.

📦 Where did this file come from?

During npm install, one of two things happened:

Prebuilt Binary Downloaded:
- If a compatible binary for your Node.js version and OS was available, better-sqlite3 downloaded it.
Local Compilation:
- If no prebuilt binary matched your setup, node-gyp compiled the C++ code on your machine using a C++ compiler (e.g., MSVC).
- The .node file was created in node_modules/better-sqlite3/build/Release/.

There is a binding.gyp file in node_modules\better-sqlite3 . Its contents:

# ===

# This is the main GYP file, which builds better-sqlite3 with SQLite3 itself.

# ===

{

'includes': ['deps/common.gypi'],

'targets': [

{

'target_name': 'better_sqlite3',

'dependencies': ['deps/sqlite3.gyp:sqlite3'],

'sources': ['src/better_sqlite3.cpp'],

'cflags_cc': ['-std=c++20'],

'xcode_settings': {

'OTHER_CPLUSPLUSFLAGS': ['-std=c++20', '-stdlib=libc++'],

'msvs_settings': {

'VCCLCompilerTool': {

'AdditionalOptions': [

'/std:c++20',

'conditions': [

['OS=="linux"', {

'ldflags': [

'-Wl,-Bsymbolic',

'-Wl,--exclude-libs,ALL',

}],

{

'target_name': 'test_extension',

'dependencies': ['deps/sqlite3.gyp:sqlite3'],

'conditions': [['sqlite3 == ""', { 'sources': ['deps/test_extension.c'] }]],

}

✅ What `binding.gyp` Confirms:

This file is used by node-gyp to compile the native C++ code (src/better_sqlite3.cpp) if needed.
It pulls in and builds SQLite3 itself via deps/sqlite3.gyp.
The config is ready to support Windows (msvs_settings) and Linux/macOS (ldflags, xcode_settings).
It uses C++20 standard for compilation.

The package.json file in node_modules\better-sqlite3 has the following (snippet):

"scripts": {

"install": "prebuild-install || node-gyp rebuild --release",

"build-release": "node-gyp rebuild --release",

"build-debug": "node-gyp rebuild --debug",

...

-------

✅ What’s Happening During `npm install`

The relevant line:

"install": "prebuild-install || node-gyp rebuild --release"

means the following happens during installation:

prebuild-install is attempted first:
- It checks if there is a matching prebuilt binary (a .node file compiled for your OS, CPU, and Node.js version).
- If found, it downloads it and places it directly into:
```
node_modules/better-sqlite3/build/Release/better_sqlite3.node
```
- This avoids needing a compiler or node-gyp.
If no matching binary is available, then:
- node-gyp rebuild --release is used to build it locally using:
  - C++ toolchain (e.g., MSVC on Windows),
  - Node headers,
  - And the binding.gyp file.

📦 What is `prebuild-install`?

It’s a tool that downloads precompiled `.node` binaries from GitHub (typically from the library’s Releases section).

Saves developers from needing a C++ build environment (like Python, Visual Studio, node-gyp setup).

Used by many native Node.js addons (e.g., `sharp`, `bcrypt`, `better-sqlite3`).

In my case, it seems that the better-sqlite3.node was built on my PC but in Sept. 2024 with Node version then most probably being v22.13.1. Even though I built the project referred to in this post later on (in 2025), probably an npm install or equivalent of an earlier project that uses the same package, resulted in the .node file being available in npm cache. So, when I later built the project discussed in this post (in 2025), it seems npm reused the already-built better-sqlite3.node binary from its local cache — originally compiled in Sept. 2024 — instead of triggering a rebuild.

[From a short Gemini chat:]
My question: Is ABI version is same as NODE_MODULE_VERSION

Gemini response:

Yes, in the context of Node.js native addons, the ABI version is indeed directly equivalent to NODE_MODULE_VERSION.

When you encounter an error like:

"Error: The module 'some-module.node' was compiled against a different Node.js version using NODE_MODULE_VERSION [X]. This version of Node.js requires NODE_MODULE_VERSION [Y]."

NODE_MODULE_VERSION [X] refers to the ABI version that the native addon was compiled against.
NODE_MODULE_VERSION [Y] refers to the ABI version of the Node.js runtime you are currently trying to use.

This error explicitly tells you that the binary interface of the compiled native module (X) is incompatible with the binary interface of your current Node.js runtime (Y).

You can find the NODE_MODULE_VERSION of your current Node.js installation by running node -p "process.versions.modules" in your terminal. There are also resources like node-abi that provide mappings between Node.js versions and their corresponding NODE_MODULE_VERSION (ABI version).

So, to reiterate:

ABI version is the general concept of the Application Binary Interface.
NODE_MODULE_VERSION is the specific integer value that Node.js uses to represent its current ABI.

Me: Is there a website giving the mapping of Node version like Node v22.13.1 to NODE_MODULE_VERSION (or ABI version)?

Gemini response extract:

Node.js Official Documentation (specifically the abi_version_registry.json file in the GitHub repository): While not presented as a user-friendly table on the main Node.js website, the actual source of truth for these mappings is within the Node.js project's GitHub repository. You can often find a JSON file that directly maps module versions.

https://github.com/nodejs/node/blob/main/doc/abi_version_registry.json
This file provides the most detailed and accurate mappings, including pre-release versions and sometimes even Electron's ABI versions. Looking at this file, you can confirm 127 for Node.js 22.x.

-----

I checked out https://github.com/nodejs/node/blob/main/doc/abi_version_registry.json . The relevant entries for me from it are:

"NODE_MODULE_VERSION": [

{ "modules": 138,"runtime": "node", "variant": "v8_13.7", "versions": "25.0.0-pre" },

{ "modules": 137,"runtime": "node", "variant": "v8_13.6", "versions": "24.0.0" },

{ "modules": 136,"runtime": "electron", "variant": "electron", "versions": "37" },

{ "modules": 135,"runtime": "electron", "variant": "electron", "versions": "36" },

...

{ "modules": 129,"runtime": "node", "variant": "v8_12.8", "versions": "23.0.0-pre" },

{ "modules": 128,"runtime": "electron", "variant": "electron", "versions": "32" },

{ "modules": 127,"runtime": "node", "variant": "v8_12.4", "versions": "22.0.0" },

{ "modules": 126,"runtime": "node", "variant": "v8_12.3", "versions": "22.0.0-pre" },

{ "modules": 125,"runtime": "electron", "variant": "electron", "versions": "31" },

{ "modules": 124,"runtime": "node", "variant": "v8_12.2", "versions": "22.0.0-pre" },

...

{ "modules": 116,"runtime": "electron", "variant": "electron", "versions": "25" },

{ "modules": 115,"runtime": "node", "variant": "v8_11.3", "versions": "20.0.0" },

{ "modules": 114,"runtime": "electron", "variant": "electron", "versions": "24" },

-----

The above "source of truth" clearly tells me:

My current Node v22.16.0 as well as my previous Node v22.13.1 both have the same NODE_MODULE_VERSION (ABI version) of 127.
My DML computer which showed the error message with NODE_MODULE_VERSION (ABI version) of 115 was using Node v20.x.x.

Hmm. So in the Node.js world, sometimes one has to look at source code to even map NODE_MODULE_VERSION (ABI version) to Node versions. That's quite a learning. I had expected there would be some document on nodejs.org website which would have a table showing this mapping.

I shared the above in a slightly edited form (as Gemini does not know about my DML computer) with Gemini. Its response is longish but I am giving it below in full because it seems to be authoritative and very informative:

You've hit on a very keen observation and a common pain point for developers working with native Node.js addons!

You are absolutely correct:

Your Node v22.16.0 and v22.13.1 both having NODE_MODULE_VERSION 127 is expected. This demonstrates that patch and even minor versions within the same major Node.js release generally share the same ABI version. The ABI only tends to change with a new major Node.js release.
Your laptop showing NODE_MODULE_VERSION 115 confirms it was running a Node.js 20.x.x version, as 115 is the ABI for the Node.js 20.x series.

And you are also correct in your frustration:

"Hmm. So in the Node.js world, sometimes one has to look at source code to even map NODE_MODULE_VERSION (ABI version) to Node versions. That's quite a learning. I had expected there would be some document on nodejs.org website which would have a table showing this mapping."

This is indeed a common sentiment. While the Node.js project strives for excellent documentation, the NODE_MODULE_VERSION mapping isn't always front-and-center on the main nodejs.org site in a simple, easy-to-find table.

Why this might be the case (and why it's a "learning"):

Focus on N-API: A significant reason for this lack of a prominent, official table is the strong push towards N-API. The ideal scenario, from the Node.js project's perspective, is that developers use N-API for native modules. If you use N-API, you don't need to worry about NODE_MODULE_VERSION because N-API provides ABI stability across Node.js major versions. The very existence of NODE_MODULE_VERSION and the need to recompile is a legacy issue that N-API aims to eliminate.
Dynamic Nature: The NODE_MODULE_VERSION is tied to breaking changes in the C++ API of Node.js or its dependencies (like V8). While predictable with major versions, it's ultimately determined by internal implementation details that change over time. Maintaining a static, perfectly up-to-date table on a website could be cumbersome and prone to being out of sync if a minor C++ breaking change necessitated an ABI bump.
Tooling Handles It: For most developers, tools like node-abi, node-gyp, and node-pre-gyp abstract away this complexity. They query the necessary information or consult their internal mappings. If you're building a native module, these tools are your primary interface, not manual lookup tables.
Source as Definitive Truth: As you've discovered, the abi_version_registry.json file in the Node.js GitHub repository is the ultimate source of truth because it's directly updated as part of the release process. For developers who need absolute certainty or are working on tooling, going to the source code is often the most reliable approach.

Your "learning" is valuable:

It highlights that while N-API is the future and ideal, the practical reality of supporting older modules or modules not yet ported to N-API means understanding the NODE_MODULE_VERSION is still crucial. And, you've learned to go to the authoritative sources (like the GitHub repo or well-maintained community tools like node-abi) when official high-level documentation doesn't immediately provide the granular detail you need.

It's definitely a nuance of the Node.js ecosystem that can catch people by surprise!

------------

Back to ChatGPT extracts (slightly edited if needed):

1. Does the compiled `.node` binary record the Node ABI or version it was built with?

Yes, indirectly:

When a native addon is built with node-gyp, the compiled binary (.node file) is a [PE/ELF/DLL] format file containing compiled machine code targeted for a specific Node ABI version.
The Node ABI version corresponds to process.versions.modules (like 127 for Node 22).
This ABI version affects how the binary hooks into Node’s internals (V8 engine, Node APIs).

However, the ABI info is not stored as a simple version tag inside the binary. Instead, it is tied to the binary’s compiled symbols and linking.

2. Does Node.js check at runtime if the binary's ABI matches the current Node version?

Yes, Node.js performs a check when loading native addons:

When you require('better-sqlite3'), Node attempts to load the .node binary.
It checks the binary’s NODE_MODULE_VERSION (ABI version) embedded in the binary header against the currently running Node.js process.versions.modules.
If they don’t match, Node throws an error like: Error: The module was compiled against a different Node.js version using NODE_MODULE_VERSION XX but Node.js version YY is running.

This is why:

A .node file compiled with Node 20 (ABI ~115) will fail if loaded in Node 22 (ABI 127).
You must rebuild the native addon whenever you upgrade Node to a version with a different ABI.

3. How does better-sqlite3 handle this?

It uses node-gyp to build the native code.

Your package.json has this "install" script:

"install": "prebuild-install || node-gyp rebuild --release"

This means if a compatible prebuilt binary is not found for your Node ABI, it compiles locally.
This ensures that the .node binary matches the exact Node ABI you are running.

4. Summary

Question	Answer
Is ABI/version info in the binary?	Yes, implicitly (in binary header)
Does Node check ABI on load?	Yes, and it errors if mismatch
Does better-sqlite3 recompile on ABI mismatch?	Yes, via `node-gyp rebuild` fallback

If you want to avoid such errors when upgrading Node, remember to clean your node_modules and rebuild native addons, for example:

rm -rf node_modules
npm install

npm rebuild better-sqlite3

Me: My view is that with this approach Node.js is playing safe. There may be a good possibility the .node file compiled in a previous Node ABI version may still run properly in a later Node ABI version. But Node.js wants to play safe. What do u say

ChatGPT:

Absolutely — your view is spot on!

Node.js enforces strict ABI version checks to prioritize safety and stability. Here’s why that’s a smart approach:

Backward compatibility at the native addon level is very fragile. Even small changes in V8 or Node’s internals can cause subtle crashes or memory corruption if a binary compiled for one ABI runs on another.
Preventing silent errors: If Node allowed mismatched ABI binaries to load, you could get unpredictable crashes, corrupted data, or security vulnerabilities that are hard to diagnose.
Explicit rebuild ensures correctness: Rebuilding the native addon guarantees the binary is compiled against the exact headers and ABI of the current Node version, avoiding all those risks.
Tradeoff: Yes, sometimes the older binary might have worked fine on a newer Node, but the risk is too high for a platform as widely used as Node.js.

So Node’s approach is a conservative safety-first design — it errs on the side of preventing potential runtime failures, even if it means some redundant rebuilds.

Me: I think your words, "So Node’s approach is a conservative safety-first design — it errs on the side of preventing potential runtime failures, even if it means some redundant rebuilds." explain it well. If I contrast it with something like Windows OS, I think Windows OS is more lax in this regard and one can use executable code built with much older Windows OSs on newer Windows OS.

ChatGPT:

Exactly — that’s a great contrast!

Windows does tend to be more backward compatible at the binary level, often supporting executables and DLLs built many years (or even decades) ago on newer OS versions. This is possible because:

The Windows API maintains a lot of legacy compatibility layers.
Microsoft invests heavily in ensuring old system calls and binaries continue to work.
The OS often uses "shims" or compatibility modes behind the scenes.

In contrast, Node.js native modules depend on very specific internal V8 and Node runtime APIs and ABIs which can change frequently between versions. Because:

The Node.js native ABI is much more volatile than the Windows API.
The binary interface is tightly coupled to Node’s internal JavaScript engine version.
Even small ABI changes can cause crashes or subtle bugs.

So Node.js takes the safer, stricter route of requiring a rebuild, while Windows chooses to maintain broad backward compatibility at some cost to complexity and possibly some performance.

Both approaches have their pros and cons — Node’s is simpler and safer for native addon developers, while Windows’s approach favors seamless user experience at the OS level.

Me: I am transitioning from a Windows/Linux programming background in period of 1990 to 2002 to, after a big break, Node.js now (frontend and backend). One great difference I am seeing is that on Windows/Linux world of those days, source code was usually proprietary and so for third party stuff one would only get executables (dlls/exes etc.) In the Node.js world, source code seems to be almost necessary even for third party stuff though as you had explained in an earlier chat. some packages could have binaries (but that is rare). Here with better-sqlite3 we have the C++ source code. What are your comments on what I have said

ChatGPT:

You're absolutely right — and your observation reflects a deep shift in software development culture and infrastructure between the 1990s/early 2000s and the modern open-source ecosystem, especially around Node.js. Here are a few key perspectives on this transition:

🔄 Then: 1990–2002 Windows/Linux World

Proprietary dominance: Most libraries and tools — even the small ones — were closed-source.
Binary distribution: Developers were given .dll, .so, or .exe files. Source code was rare unless you paid for a license or were in academia.
Source = power: Having source code was a big deal. Open source was often associated with the GNU/Linux world, and not yet mainstream in corporate development.
Portability issues: Porting binaries across platforms was tricky, so you'd often be locked to one OS or compiler.

🌍 Now: Node.js & the Modern Open Source World

Source code everywhere: Most packages on npm include their full source — even ones with native code like better-sqlite3. It's not only expected but essential for cross-platform builds and debugging.
Open by default: The default development model is collaborative and transparent. GitHub + npm = shared code and shared responsibility.
Build pipelines as infrastructure: Tools like node-gyp, prebuild-install, cmake-js, and GitHub Actions allow automatic building of binaries across OS/arch/Node versions.
Community validation: Source visibility increases trust. If a package is buggy or suspicious, anyone can inspect it — no black box.
Developer flexibility: You can debug, patch, or even fork most packages easily because the source is right there.

🧠 Why This Matters for Native Addons

Native modules (like better-sqlite3) need to compile for your specific system and Node version.
This means having source code (C/C++) available isn't just helpful — it's necessary.
If there were only a .dll or .so, it would break with every Node ABI change — so the whole community model depends on source availability.

🤔 Bottom Line

You’re witnessing a fundamental evolution:

Old Model	New Model
Closed source by default	Open source by default
Binaries distributed	Source code distributed
Platform-specific builds	Cross-platform source builds
Vendor lock-in	Community-led development
Debugging = hard without source	Debugging = expected with source

It’s a shift from binary dependence to source empowerment. And as someone transitioning into the Node.js/open-source era, your background gives you a strong foundation to appreciate how far things have come — and why the modern approach is so powerful.

-------------------------

Me: One down side of Open Source model is that one has to build quite often. I mean, upgrade of Node.js on my PC means the old projects may need a rebuild to work properly. That seems to me to be a disadvantage as compared to the old model where once you have a tested exe file/program, you need not have to worry about rebuilding the exe file as the Windows platform changes. Yes, for efficiency purposes you may have to refactor the old app to use new features provided by a new Windows OS. But if that is not a requirement, the old exe would just run on the Windows upgrade.

ChatGPT:

That’s a very thoughtful and accurate observation — and you're absolutely right again. The need to rebuild in the open-source + native module world is one of the tradeoffs for flexibility and transparency. Let’s break this down a bit:

✅ Old Proprietary Binary Model — Pros (as you said)

Tested once, works for years: A .exe or .dll built on Windows 95 might still run on Windows 10 or even Windows 11. That level of binary compatibility is extraordinary.
No build environment needed: You didn’t need a compiler, dependencies, or toolchains to use a binary.
Easy redistribution: You could copy binaries around, and they just worked.
Upgrades didn’t break things: OS upgrades rarely forced you to rebuild your app or third-party tools.

🧩 Why this was possible: Microsoft made great effort to preserve API/ABI-level compatibility over time, even emulating older behaviors internally (think “wow64”, SxS DLLs, etc.).

⚠️ Open Source / Node.js / Native Module Model — Drawbacks

Rebuilds are common: Upgrade Node.js → rebuild native modules (e.g., .node files).
Tools needed to build: You need node-gyp, Python, C++ compilers, etc., which can be painful to set up correctly, especially on Windows.
More fragile compatibility: The tight coupling between Node ABI and V8 internals means older binaries can easily become unusable.
Automation helps, but isn’t perfect: Tools like prebuild or prebuild-install reduce rebuilds but can’t cover every platform or Node version.

🧭 Tradeoff Summary

Aspect	Old Model (Windows EXEs)	Open Source (Node Native Modules)
Binary Compatibility	Very strong (decades!)	Weak (ABI changes frequently)
Need to Rebuild	Rare	Frequent (e.g., on Node upgrades)
Source Access	Rare, closed	Common, open
Portability (platform/arch)	Poor	Excellent with source + toolchain
Developer Freedom	Limited	High — debug, patch, extend

🧘‍♂️ Philosophical Difference

Old world (closed binaries): Prioritized ease of use and long-term stability — but limited what you could understand or change.
Modern open-source world: Prioritizes transparency, control, and adaptability — at the cost of build complexity and more frequent maintenance.

🚀 Closing Thought

You’re absolutely right to notice the downside — frequent rebuilds are a real maintenance burden, especially when just trying to "get stuff done." But at the same time, having the source code as a first-class citizen gives developers deep power and flexibility, something that was much harder to achieve in the earlier proprietary world.

It's not better or worse — just a different set of tradeoffs.

----------

Me: Good to have this chat with you. I have been able to confirm my understanding of some big differences btw Node.js dev and older Windows/Linux dev. Note that while Linux OS was open source, lot of the software one would use on it like say Oracle database would not be open source. I also got a better understanding of some points which were grey earlier.

ChatGPT:

I'm really glad to hear that — and it’s been a pleasure having this thoughtful chat with you!

You're right again: while Linux itself was open source back then, much of the software ecosystem around it (e.g., Oracle DB, commercial compilers, proprietary libraries) was very much closed source and binary-distributed. Now, in the Node.js world (and modern open source in general), source-first development has become the norm — and it really changes how we think about software.

Just to summarize the key takeaways from your journey:

✅ Binary vs. Source-centric Models:

Older model: “Here’s a tested .exe/.dll — just run it.”
Newer model: “Here’s the source — build it for your system.”

✅ Compatibility Expectations:

Older: Windows goes out of its way to keep old binaries working.
Newer: Node.js changes ABI often; rebuilds are expected.

✅ Open Source Culture:

Shifted from niche (1990s) to mainstream and essential today.
Gives flexibility, transparency, but requires more tooling/setup.

✅ Native Module Fragility:

Native modules (like better-sqlite3) need to match ABI of Node.
But tools like prebuild-install ease this where possible.

Me: Can you tell me a little more about Node.js ABI

ChatGPT:

Absolutely! The Node.js ABI (Application Binary Interface) is a key concept when working with native addons — like better-sqlite3 — that compile C or C++ code into .node binary modules. Here’s a concise but complete overview to help you understand what it is and why it matters.

🧠 What Is the Node.js ABI?

The ABI defines the binary interface between the Node.js runtime and native modules.
It governs things like:
- How functions are called (e.g., parameter passing, stack layout)
- Memory alignment and structure layout
- Data type sizes
- How Node exposes C++ internals (like V8 or libuv) to addons

When Node.js is updated (especially with a new V8 version), its ABI often changes.

🧬 ABI vs. API

Term	Meaning
API	Application Programming Interface (source-level) — e.g., methods exposed via Node’s `n-api` or V8
ABI	Application Binary Interface — compiled/binary-level compatibility between compiled native code and Node runtime

A native addon that uses Node’s internal headers and is compiled with Node 20 won’t work with Node 22 unless it’s recompiled — because the ABI version changed.

🔢 Node ABI Version = `NODE_MODULE_VERSION`

This is a numeric version representing the ABI.
You can see it by running:

console.log(process.versions.modules);  // e.g., '127' for Node 22.x

Every major Node version has its own ABI version. Examples:

Node.js Version	ABI (NODE_MODULE_VERSION)
Node 16.x	93
Node 18.x	108
Node 20.x	115
Node 22.x	127

When Node loads a .node binary, it checks the binary's ABI version against its own. If they don’t match, you get a runtime error like:

Error: The module was compiled against NODE_MODULE_VERSION 115, which is not compatible with the current version 127.

📦 How Native Modules Handle This

Modules like better-sqlite3 include a line in package.json:
```
"install": "prebuild-install || node-gyp rebuild"
```
This tries to:
1. Download a matching prebuilt binary (if available),
2. Or build it locally for the current ABI.
That’s why even if you have the .node file from before, Node will refuse to load it if the ABI doesn't match.

💡 How to Avoid ABI Issues

Rebuild native modules after upgrading Node:
```
npm rebuild
```
Use tools like nvm to manage multiple Node versions.
Stick to Node’s N-API if writing your own native modules — it's ABI-stable, unlike direct V8 APIs.

🏁 Summary

Node ABI defines how Node.js communicates with compiled native addons.
ABI changes with major Node versions (new V8 engine).
Native modules must match ABI version — otherwise Node won’t load them.
The ABI version is represented by NODE_MODULE_VERSION.

Me (mistaken part of question edited out): Most node.js packages would be in JavaScript and that code is essentially interpreted by Node.js runtime. So they don't need to worry about either Node.js ABI. Am I right?

ChatGPT:

Yes, you're absolutely right — and this is an important distinction.

✅ Most Node.js packages are written entirely in JavaScript (or TypeScript → JS)

These packages run inside the Node.js runtime, which interprets or JIT-compiles the JavaScript code via the V8 engine.
They don’t interact with the lower-level internals (like memory layout, binary calling conventions, etc.).
So they don’t depend on Node.js’s ABI (Application Binary Interface) at all.

➡️ Result:
You can upgrade Node.js, and 99% of JavaScript-only packages will just work — no rebuild needed, no compatibility concerns.

❗ ABI/Native Addon Concern Only Applies To:

Packages that include native code (C/C++), often compiled via node-gyp.
These packages produce .node binaries that are dynamically loaded by Node.js.
Examples:
- better-sqlite3
- node-sass (old versions)
- bcrypt (unless using pure JS fallback)
- sharp (image processing)

➡️ These require the .node binary to be ABI-compatible with the current Node version — or else they’ll need to be rebuilt or prebuilt for that version.

🎯 Summary

Package Type	Depends on ABI?	Affected by Node Upgrade?
JavaScript-only (most)	❌ No	✅ Generally safe
Native addon (e.g., C++)	✅ Yes	❗ May break, needs rebuild

So your understanding is exactly right — the ABI concern is a corner case, but an important one when you hit it. Most packages never touch it.

----------

I then asked a question about Node.js API but I meant the API interface to C/C++ code. My question: Which packages will use Node.js API (as against ABI)?

ChatGPT:

🧩 Node.js API vs ABI — Who Uses What?

To recap:

ABI (Application Binary Interface): Concerns compiled native code (.node files).
API (Application Programming Interface): Refers to the functions/methods exposed by Node.js — mostly in JS, but also in C/C++ via headers.

✅ Who Uses the Node.js API?

1. JavaScript Developers (JS API)

Most developers use Node’s JavaScript-level API, such as:

fs.readFile, http.createServer, crypto.randomBytes, etc.
These are part of Node’s standard library, built on top of the lower-level internals.
No ABI involved here — it’s all JS.
✅ Most packages use Node.js API only — and stay safe across upgrades.

2. Native Addon Developers (C/C++ Node API)

Native addon authors may use:

A. 🔥 V8/Node Internals (NOT Stable)

Directly access V8 engine and Node internals.
Tightly coupled to Node’s internals → ABI breaks often.
Examples:
- better-sqlite3
- node-sass (older versions)
- ❗ These need rebuilds for each Node version (unless a prebuild exists).

B. 🧱 N-API (Node API) — Stable C Interface

Introduced to solve ABI breakage problems.
Defined in node_api.h, maintained by Node.js core team.
Binary compatibility across Node versions — no need to rebuild!
✅ Packages using N-API (like node-addon-api or bcrypt new versions) work across multiple Node versions.

🧰 Summary Table

Developer Type	Uses Node API?	Uses ABI?	Rebuild Needed on Node Upgrade?
JS package authors	✅ Yes (JS)	❌ No	❌ No
Native addon (V8 API)	✅ Yes (C++)	✅ Yes	✅ Yes
Native addon (N-API)	✅ Yes (C/N-API)	✅ Yes	❌ No (if done properly)

🧠 Final Thoughts

Most Node.js packages use the JavaScript API — safe and portable.
Native addons:
- If they use V8 internals, they are fragile (breaks easily).
- If they use N-API, they are robust and stable.

So, if you're using or building native modules, prefer N-API when possible. For general JS dev, the Node API is all you need — and it avoids all these compatibility headaches.

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I first commented about the difference between the two APIs (JS and C/C++) interfaces. In the next comment I mentioned that I had got confused with the Node.js API term and presumed that Node.js API term was used only for C/C++ code. I also said, "Now I think the Node.js API term and its variations are clear to me."

ChatGPT (response to 2nd comment):

I'm really glad to hear that — and you're not alone! Many developers (especially those with experience in lower-level systems like C/C++ or older Windows/Linux platforms) find the term "Node.js API" a bit ambiguous at first.

Here's a final summary to help cement it:

✅ When people say “Node.js API”, it can mean:

Context	Meaning	Used By
JavaScript Devs	The standard modules exposed in JS (`fs`, `http`, etc.)	99% of Node.js users
Native Addon Devs	The C/C++ interface exposed via `node_api.h` (N-API) or `v8.h` (V8 internals)	Native addon authors

🔁 So yes — the same term is used for both, depending on context. That’s why it’s confusing at first!

🔧 Tip to remember

If you're writing regular Node.js apps in JavaScript/TypeScript → "Node.js API" = JS APIs (safe, stable).
If you're compiling C++ code that plugs into Node.js → "Node.js API" = C/C++ headers (possibly fragile unless using N-API).

You're now fully equipped with this conceptual clarity — and it’s an important foundation if you’re digging deeper into how Node.js interacts with native modules or the OS.

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Me: Besides C/C++, can one not use other languages like Java or Pascal (if it is still around) to write 'native' Node.js code that plugs in to Node.js via its N-API or V8 internals

ChatGPT:

Great question — and a very insightful one, especially given your background!

🧩 Short Answer:

In practice, C and C++ are the only languages officially supported for writing native Node.js addons using N-API or V8 internals.
Other languages can be used, but only indirectly — usually through C/C++ interop or via custom bridges.

🔧 Why Only C/C++ for Native Addons?

Node.js internals (like V8) and N-API are C/C++ headers.
- V8 is a C++ library.
- N-API is a C interface designed for ABI stability.
Native addons are compiled into .node (shared library) files, which must expose a C-style entry point that Node can load.

🔁 What About Other Languages?

✅ Possible — With Wrappers or Bridges

You can write code in other compiled languages like:

Language	How It Could Work	Practical?	Notes
Rust	Use `napi-rs` or FFI	✅ Yes	Most popular alternative to C/C++ for Node.js native code.
Go	Use `cgo` + C wrapper	⚠️ Possible	But leads to complex toolchains and large binaries.
Java	Use JNI (Java Native Interface) + C bridge	⚠️ Rare	Not a typical choice. Overkill and complex setup.
Pascal	If compiled to a shared library with a C-compatible ABI	❌ Rare	Very niche; nearly no community support.
Zig	Can generate `.node` files with C ABI	🧪 Experimental	Clean interop, but less tooling than Rust.

✅ Best Alternatives to C/C++ Today

Language	Library / Toolchain	Highlights
Rust	`napi-rs`, `neon`	Safe, modern, growing ecosystem.
C	Direct use of N-API	Lean, portable.
C++	With or without `node-addon-api`	Standard for complex native addons.

🚫 JavaScript-only developers?

For regular Node.js apps: just use JavaScript/TypeScript. You don’t need to touch N-API or native addons unless:

You need performance-critical code.
You need to bind to an existing C/C++ library.

🧠 Summary

Yes, you can theoretically use languages like Java, Pascal, Go — but it’s complicated and rarely done.
C/C++ (and increasingly, Rust) are the practical choices for native Node.js development.
Node.js only requires that the native addon exposes a C ABI that it can load into V8 — how you get there is up to you, but the toolchain is most mature for C/C++.

------------

Me: "In practice, C and C++ are the only languages officially supported for writing native Node.js addons using N-API or V8 internals.

Other languages can be used, but only indirectly — usually through C/C++ interop or via custom bridges." ... Now I get it. I was wondering why there was talk only of C/C++ in the context of these native related packages in Node.js ecosystem (which includes React Native). Hmm. So Node.js is heavily biased towards C/C++ for Native code as against other compiled languages.

ChatGPT:

Exactly — you've nailed it. ✅

💡 Here's the essence:

Node.js is built on a foundation that speaks C and C++ natively, so it naturally expects native modules to be written in those languages. That’s why:

Node core itself (like libuv, V8 bindings, etc.) is in C/C++.
Native addons must match the ABI expected by Node, which is a C ABI.
Tooling like node-gyp, prebuild, and node-addon-api are all designed for C/C++.

🔍 Why not other languages like Java or Pascal?

They:

Don’t output shared libraries that match Node’s expected ABI out of the box.
Often have their own runtime (e.g., Java's JVM), which complicates embedding.
Don’t have strong ecosystem/toolchain support for Node.js integration.

🧭 But if you really want to use another language…

Here’s how they can fit in indirectly:

Language	Bridge Path	Viable?
Rust	`napi-rs`, `neon`, FFI with `node-gyp`	✅ Actively used
Go	Compile to shared lib → wrap in C	⚠️ Tricky, large binary
Java	JNI + C wrapper + IPC maybe	🚫 Overkill unless embedding
Python	Use as subprocess or via `ffi-napi` in JS	⚠️ Common for scripting, not performance
Pascal	Only if it compiles to compatible shared lib	❌ No real support today

Rust Note

Rust is becoming increasingly viable thanks to community tools like napi-rs, but it is not officially supported by Node.js core.

🛠️ React Native Note

Even in React Native (which uses Java/Kotlin for Android, Objective-C/Swift for iOS), the JavaScript-to-native bridging layer is carefully structured — and again, C++ often sits in the middle via JSI (JavaScript Interface).

🎯 Final Thought

So yes — Node.js is heavily biased toward C/C++ for native code, not due to favoritism, but because:

It’s the only safe, stable, ABI-compatible way to extend Node.js natively.
The entire Node and V8 ecosystem is C/C++-centric at the native level.

You're now seeing behind the curtain of how the whole ecosystem really fits together — that's a big leap forward in understanding!

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