Notes on JS bundlers: esbuild, Webpack, Metro; JS apps & utils: Cross-platform features, performance vis-a-vis C++/C#

Last updated on 13 Sept. 2025
Given below are edited extracts from a recent Gemini chat, 'esbuild Node.js Project Setup Confirmation'. The chat was a parallel chat to the chat covered in my recent post: Notes on JavaScript minifiers and bundlers, npm link, command line JS utils.

Note: Some parts of this post cover using esbuild to create a single minified and bundled scrapeBlogpost.js which, IFIRC, could be (potentially) run cross-platform using: node scrapeBlogpost.js without any additional files/folders like node_modules. In a later post, I have covered how adding yargs package raised problems for creating single minified bundle .js CLI file.

Some parts of this post mention pkg and a later part of the post mentions that it has been deprecated. For further info., please a section of another post of mine: Size of pkg created bundled executable vs minified JS bundle; Node.js Single Executable Applications (SEA) vs. pkg. 

Me: in a previous chat u introduced me to esbuild for a command line node project on Windows to create a minified .js file in dist folder that could be independently run with node. r u with me so far

Gem: Yes, I recall our previous conversation. We discussed using esbuild for a Node.js project on Windows to bundle and minify a JavaScript file into a dist folder, creating an output file that could be run independently with the node command.

The setup involved:

  • A package.json file.

  • An index.js file as the entry point.

  • A build script in package.json using esbuild with a command like esbuild index.js --bundle --minify --outfile=dist/main.js.

  • The output dist/main.js file being runnable with node dist/main.js.

Is there anything else I can help you with regarding this project or esbuild?

Me: tell me more about esbuild

Gem: esbuild is a modern and extremely fast JavaScript bundler and minifier. Unlike many of its competitors, it's not written in JavaScript. Instead, it's written in Go, a language known for its high performance and ability to utilize multi-core processors. This design choice is a key reason for esbuild's speed, often touting itself as being 10 to 100 times faster than other bundlers like Webpack and Rollup.

It achieves this speed through several design choices:

  • Parallelism: esbuild is designed to use all available CPU cores to perform tasks like parsing and code generation concurrently.

  • Minimal Passes: It processes code in a small number of passes, avoiding the need to generate a full Abstract Syntax Tree (AST), which is a common performance bottleneck for other tools.

  • Native Code: Being a compiled Go executable, it runs much faster than tools that rely on a JavaScript runtime.

Key Features and Benefits

esbuild's focus on speed and simplicity makes it a popular choice for a variety of tasks. Its core features include:

  • Bundling: It can combine multiple JavaScript files into a single output file, which reduces the number of network requests a browser needs to make to load a page.

  • Minification: It shrinks the size of your code by removing unnecessary characters like whitespace and comments, and shortening variable names.

  • Transpilation: esbuild has built-in support for TypeScript and JSX, allowing you to use these languages without needing separate tools like Babel or TypeScript's own compiler.

  • Tree Shaking: It automatically removes unused code from your bundles, further reducing the file size.

  • APIs: It offers a command-line interface (CLI) for simple tasks and a JavaScript API for more complex build scripts.

  • Watch Mode and Local Server: For development, it has features that automatically rebuild your project when files change and can even start a local server to serve the output.

While it may not have all the advanced features or extensive plugin ecosystems of older, more mature bundlers, its focus on speed and ease of use has made it a foundational component of many modern build tools and frameworks, such as Vite, Angular, and Rails. Introduction to esbuild This video provides a good introduction to esbuild, including its benefits and how to use it.


Me: In my React js or node express or next.js or even react native projects they all used some other bundlers. None used esbuild. pl comment

Gem: That's an excellent observation. While esbuild is known for its speed, it's often used as a component within other build tools rather than as the primary, standalone bundler for large-scale application frameworks.

Here's why you see different bundlers in those projects:

1. Specialization and Feature Set ⚙️

Bundlers like Webpack and Rollup have been around for a long time and have built up extensive ecosystems with thousands of plugins and loaders. These plugins handle complex tasks that a fast, simple bundler like esbuild doesn't, such as:

  • Code Splitting and Lazy Loading: Optimizing load times by splitting your code into smaller chunks that can be loaded on demand. Webpack is especially strong here.

  • Asset Management: Handling non-JavaScript files like CSS, images, and fonts directly within your JavaScript code. This requires specific loaders.

  • Advanced Optimizations: Performing more aggressive or customized code transformations and optimizations that go beyond simple minification.

While esbuild is fast, it intentionally keeps its core feature set focused on bundling and minification to maintain that speed. For most complex applications, developers need the flexibility and advanced features offered by other bundlers.

2. Integration with Frameworks 🤝

The frameworks you mentioned have their own preferred or built-in tooling, and they've often integrated esbuild as a performance-enhancing part of that system.

  • Next.js: This framework originally used Webpack. While it still offers Webpack for build customization, it has since shifted to its own Rust-based compiler called Turbopack, which is much faster and is built specifically for the unique needs of Next.js projects.

  • React Native: The default bundler for React Native is Metro. Metro is highly optimized for the specific needs of a mobile development environment, including features like Fast Refresh and the ability to work with native modules and assets for both iOS and Android. While there are some community-driven projects to use esbuild with React Native, Metro is the standard.

  • Vite: This is a great example of a tool that uses esbuild. Vite, a popular alternative to create-react-app, leverages esbuild for its lightning-fast development server. It uses esbuild for quick transpilation and then relies on Rollup for the final production build, striking a balance between development speed and production-ready optimizations.

Me: Oh! so the frameworks get tied up with specific bundlers and so typically one uses that bundler when using a particular framework. am i right

Gem: Yes, you are exactly right. The frameworks you mentioned—Next.js, React Native, and others—tend to be "opinionated" about their build process. This means they come with a specific bundler or build toolchain that is deeply integrated into the framework's core functionality.

This is a fundamental design choice that offers several key advantages:

  • Optimized Performance: The framework's creators can fine-tune the bundler for the specific needs of that framework. For instance, Next.js's Turbopack is built on Rust to be incredibly fast, with features like lazy bundling that are perfectly suited for a server-side rendering framework. React Native's Metro is optimized for the unique demands of mobile development, such as hot reloading and handling platform-specific assets.

  • Reduced Configuration: As a developer, you don't need to spend time configuring a complex build process from scratch. The framework handles it for you, allowing you to focus on building the application. This is a huge benefit, especially for beginners.

  • Seamless Developer Experience: The integrated bundler enables powerful features that are critical for modern development, like Hot Module Replacement (HMR) and Fast Refresh. These features automatically update your code in the browser or on the device as you save, without losing the application's state. This is only possible when the bundler and the framework are designed to work together.

  • Consistent Ecosystem: By standardizing on a bundler, the framework ensures that plugins and community tools are all built to work with the same system, which reduces the chances of compatibility issues.

So, while you can technically swap out bundlers in some cases, it's generally not recommended for most projects, especially with frameworks like Next.js and React Native. The built-in tooling is an essential part of the framework's value proposition.


Me: Ok. but when we come to simple command line nodejs tools like scrapeblogpost , we now have more choice for minifiers cum bundlers and so we could easily opt for esbuild. am i right

Gem: Yes, that is absolutely correct. When it comes to a simple, standalone command-line tool, esbuild is an excellent choice.

Here's a breakdown of why it's a perfect fit for a project like "scrapeblogpost":

  • Speed is a Top Priority: The primary goal of a command-line tool's build process is to be fast and get the job done. You're not worried about a browser's a development server, or Hot Module Replacement (HMR). esbuild's core strength—its speed—becomes the most valuable feature. Its near-instant bundling and minification make for a very efficient development workflow.

  • Minimalist Configuration: Unlike complex bundlers that require extensive configuration files (webpack.config.js), esbuild can often be used with a single command from your package.json script. This keeps your project lightweight and easy to understand.

  • Single, Portable Output: A command-line tool benefits from being a single, executable file. Bundling all your code and its dependencies into one .js file, like dist/main.js, makes it easy to distribute and run anywhere without needing to run npm install on the target machine. This is exactly what we discussed in our previous conversation.

  • Built-in TypeScript and JSX Support: If your command-line tool uses TypeScript or JSX for its logic, esbuild can transpile that code without any additional loaders or plugins, further simplifying your build process.

  • Focused Feature Set: A command-line tool typically doesn't need the advanced features of a massive bundler, such as code splitting for different routes or sophisticated asset management. esbuild's focused feature set aligns perfectly with these more straightforward requirements.

In essence, while large, client-side frameworks have complex needs that are best served by their own specialized bundlers (often built on top of or in conjunction with esbuild), a simple Node.js tool or library is where esbuild truly shines as a direct, no-fuss solution.

Me: great explanations .... Now what we get is an optimized single all in one js file. can i say that

Gem: Yes, that is a perfect way to describe the result of using a bundler like esbuild for a simple command-line tool.

The output is an optimized, single, "all-in-one" JavaScript file.

Here's why that's a good summary:

  • Optimized: The code has been processed to be as small as possible through minification (removing whitespace, comments, and shortening variable names) and tree-shaking (eliminating any unused code).

  • Single: All of your source code files and their dependencies have been combined into one file.

  • "All-in-one": The final file is self-contained and can be run independently using the Node.js runtime, without needing the node_modules directory or any other local dependencies.

This is the exact purpose of using a tool like esbuild for a project like your scrapeblogpost tool—to transform a complex collection of source files into a single, efficient, and easily distributable artifact.

Me: This single .js file becomes our 'executable' for distribution on a cross platform basis - any platform that runs node - windows/linux/macos etc.

Gem: Yes, you are completely right. This single .js file, optimized and bundled by esbuild, effectively becomes a cross-platform executable for any environment that has the Node.js runtime installed.

It's a powerful concept because you don't need to create separate build artifacts for each operating system. The same file will work seamlessly on:

  • Windows

  • Linux

  • macOS

  • Even other environments like a Docker container or a serverless function

The reason for this is that the Node.js runtime acts as a universal interpreter for your JavaScript code. Your code doesn't directly interact with the operating system's kernel. Instead, it interacts with the Node.js environment, which in turn handles the low-level communication with the operating system, regardless of whether it's Windows, Linux, or macOS.

This is a key advantage of building command-line tools with Node.js and a bundler like esbuild—it provides platform independence right out of the box.


Me: Great. ... Now lets make the discussion tighter by bringing in comparison with native OS programs performance. Let us take windows os. As we need to bring up Node process and then that process reads the single .js file and then interprets it, it will surely be slower than if we had a C#/VB.NET program exe doing the same work. am i right

Gem: Yes, your reasoning is sound. A compiled C# or VB.NET executable will almost always outperform a Node.js script for a command-line tool, especially for tasks with a lot of heavy computation.

The performance difference comes down to the fundamental nature of how these programs run.

1. The Startup Overhead of the Runtime

For a C# or VB.NET application, the .exe file is a compiled binary. When you launch it, the Windows OS loader executes the program directly. While there's a small overhead for the .NET Common Language Runtime (CLR) to start up, it's generally minimal.

In contrast, when you run a Node.js script, you're not executing your code directly. First, the operating system must launch the node.exe process. Only then can the V8 JavaScript engine within that Node.js process load, parse, and Just-In-Time (JIT) compile your JavaScript file before it can begin executing your code. This initial bootstrapping process adds a noticeable overhead, particularly for short-lived command-line tasks.

2. Compiled vs. Interpreted Languages

  • C# and VB.NET are statically typed and compiled languages. They are translated into an intermediate language (IL) and then JIT-compiled into highly optimized native machine code. This process happens once, and the resulting code runs very close to the metal, leveraging the full power of the CPU.

  • JavaScript is a dynamically typed, interpreted language. Although the V8 engine is incredibly fast and uses JIT compilation to optimize "hot" code paths, it still has to analyze and compile the code at runtime. This can introduce performance penalties, especially for CPU-bound tasks. For a quick command-line script, a lot of the code might not get a chance to be fully optimized before the script finishes.

For a tool like "scrapeblogpost" which is primarily I/O-bound (reading web pages, writing to a file), the difference in performance might not be as dramatic because the program spends most of its time waiting for network or disk operations, not on CPU-intensive work. However, for tasks that involve complex calculations or data manipulation, the native C# or VB.NET application would be significantly faster.


Me: OK. Now lets bring in the pkg stuff you had talked about in the previous chat. this pkg converts the dist .js file into an OS exe. am i right

Gem: Yes, that is exactly what the pkg tool does. It's a command-line utility that takes your bundled JavaScript file and turns it into a fully standalone, native OS executable.

The magic of pkg is that it packages a minimal, self-contained version of the Node.js runtime alongside your code and all its dependencies. When you run the resulting .exe on Windows (or a .bin file on Linux, or an app bundle on macOS), it's not simply executing your JavaScript; it's first launching that embedded Node.js environment, which then executes your bundled JavaScript file from an internal "snapshot" file system.

This solves the two major problems we discussed earlier:

  • No Node.js Installation Required: The end user doesn't need to have Node.js or npm installed on their machine. You can simply give them the single executable file.

  • Simple Distribution: You can distribute your command-line tool as a single, double-clickable file, just like a traditional application.

This process gives you the convenience of distributing a native application while still using JavaScript for your development.

This video demonstrates how to create an executable file from JavaScript code using Node.js and the pkg package.

Creating a Node.js executable

Me: Got it. so we get quicker load of node and our specific app as it is all bundled together. but once loaded, its performance may be comparable to running node.js as a separate process that interprets the dist/.js file. am i on right track

Gem: You are on the right track. The main benefit of using pkg is to eliminate the startup overhead and the dependency on a pre-installed Node.js runtime.

Startup Performance

When you run a traditional Node.js script:

  1. The operating system locates the node.exe executable.

  2. The node.exe process starts.

  3. The Node.js runtime loads, which includes initializing the V8 engine and its built-in modules.

  4. The runtime then has to find, load, and parse your main script and all of its dependencies from the file system. Each require() call can involve file I/O operations, which are relatively slow.

When you run a pkg executable, this process is significantly streamlined. The Node.js runtime and all your bundled code are already contained within the single executable file. This means there's no need for file system lookups or reading dozens of separate files. This drastically reduces the time it takes for your program to start up and begin executing code.

Runtime Performance

Once your application has started and is running, the performance is comparable to a regular Node.js process. The JavaScript code inside the pkg executable is still being interpreted and JIT-compiled by the same V8 engine that powers a standard Node.js installation. pkg is primarily a packaging and distribution tool, not a performance optimizer for the runtime itself.

In summary, the key gain from pkg is:

  • Faster startup time because everything is bundled together.

  • Simplified distribution because no Node.js installation is required.

The core execution speed for CPU-bound tasks remains the same as running the script directly with Node.js.


Me: superb explanations ... i am getting a good overall picture of this .... Now going one step further . For command execution speed, interpretation of JS will be a bottleneck as compared to compiled C#/VB.NET. am i right

Gem: Yes, your assumption is correct. A compiled C# or VB.NET program will have a significant performance advantage over a JavaScript program running on Node.js, especially for tasks that are CPU-bound (e.g., number crunching, complex data manipulation). This is because of the differences in their compilation and execution models.

C# and VB.NET: Ahead-of-Time (AOT) and Just-in-Time (JIT) Compilation

C# and VB.NET code are first compiled into an intermediate language called Common Intermediate Language (CIL), or sometimes Microsoft Intermediate Language (MSIL). This CIL is then executed by the .NET Common Language Runtime (CLR). The CLR uses a Just-in-Time (JIT) compiler to convert CIL into native machine code at runtime.

The key points are:

  1. Intermediate Language: The initial compilation from source code to CIL is a simple, straightforward process.

  2. Highly Optimized JIT: The .NET JIT compiler is extremely sophisticated. It has a full view of the CIL and can perform aggressive, complex optimizations before the code runs. It compiles the CIL into highly optimized native machine code that is specific to the user's hardware.

  3. Tiered Compilation: The .NET runtime can use a tiered approach. It might start with a quick, less-optimized compilation to get the program running faster, and then, for "hot" or frequently used code paths, it will recompile them in the background with much more aggressive optimizations.

Node.js and JavaScript: A Different JIT Approach

Node.js uses Google's V8 JavaScript engine. V8 also uses a JIT compiler, but it operates differently due to JavaScript's dynamic nature.

  1. Initial Interpretation: V8 first uses an interpreter (Ignition) to quickly convert the JavaScript code into a lightweight bytecode. This allows the program to start running immediately.

  2. Adaptive Optimization: While the code is being interpreted, V8's profiler identifies "hot" code paths—functions or loops that are executed frequently.

  3. Optimizing Compiler: The profiler sends this "hot" code and type information to an optimizing compiler (TurboFan), which then compiles it into highly optimized native machine code.

The fundamental difference lies in static typing vs. dynamic typing. C# and VB.NET are statically typed languages, meaning the data type of every variable is known at compile time. This gives the .NET JIT compiler a massive advantage as it can make firm assumptions and apply more aggressive optimizations, knowing exactly what kind of data it's working with. JavaScript, being dynamically typed, requires the V8 engine to constantly make and check assumptions about variable types at runtime. If a type changes, the V8 engine has to de-optimize the code and fall back to a less-optimized version, adding overhead.

For a CPU-heavy task, the consistently optimized native code from the .NET JIT will outperform JavaScript's adaptive, and potentially de-optimizing, process.

Me: I see. .... Is there not a possibility of compiling Javascript code for a specific target machine & OS thereby reducing interpretation time.

Gem: Yes, that's a key area of development in the JavaScript world. While the traditional model relies on a runtime like Node.js's V8 engine to perform Just-in-Time (JIT) compilation, there are indeed tools and technologies that aim to compile JavaScript code Ahead-of-Time (AOT) into native machine code.

The goal of AOT compilation is to bypass the JIT overhead entirely by doing the heavy-lifting of compilation during the build process.

How AOT Compilation Works for JavaScript

AOT compilers for JavaScript are still a relatively niche area, but they are gaining traction. They typically work by:

  1. Parsing and Static Analysis: The compiler analyzes the entire codebase to understand its structure and data flow, including all dependencies.

  2. Type Inference: Since JavaScript is dynamically typed, the AOT compiler has to make educated guesses about the data types of variables. Tools like TypeScript greatly assist this process by providing explicit type information, which allows the compiler to make more aggressive optimizations.

  3. Code Generation: The compiler translates the code into a lower-level language or an intermediate representation, which is then compiled into a final, native executable for the target OS (Windows, Linux, macOS) and architecture (x86, ARM, etc.).

This process eliminates the JIT "warm-up" time and the need for a separate runtime installation, resulting in a single, self-contained binary.

Notable AOT Compilers and Their Use Cases

  • pkg & nexe: As we discussed, these tools are a form of AOT compilation. However, it's more accurate to call them packaging tools. They bundle the Node.js runtime and your minified JavaScript code into one executable. The core JS code is still run by a JIT-compiler (V8), it's just that the runtime is now self-contained in the executable. This is a pragmatic solution for distribution, but it does not provide the performance benefits of a truly native binary.

  • Deno Compile: The Deno runtime, a Node.js alternative, includes a built-in deno compile command. This command also creates a single executable, but it's a more advanced form of bundling. It packages a snapshot of the Deno runtime with your application and performs a level of static analysis during compilation, which is a step closer to true AOT.

  • NectarJS: This is an example of a more ambitious, "true" AOT compiler for JavaScript. It's designed to compile a subset of JavaScript directly to native code. While it's a very interesting project, it's still considered a niche tool and doesn't support the full range of JavaScript features or the vast ecosystem of Node.js modules.

  • Bun: While not strictly an AOT compiler in the traditional sense, the Bun runtime is written in a low-level language (Zig) and boasts incredible speed by performing its own set of optimizations. It is seen as a modern alternative to Node.js that prioritizes performance.

Me: interesting. one could also look at typescript code alone compilers as typescript brings in heavy level of (static) data typing

Gem: You're touching on a crucial point. The strong static typing in TypeScript makes it a much better candidate for a true Ahead-of-Time (AOT) compiler.

The traditional TypeScript compiler (tsc) doesn't compile to native machine code. It's a transpiler that converts TypeScript code into plain JavaScript. The output is still a .js file that has to be interpreted by a runtime like Node.js.

However, the TypeScript team at Microsoft has been working on a significant project to port the TypeScript compiler to a native language (Go). This native version of the compiler, currently in preview, aims to drastically improve performance for type-checking and project builds.

This effort, codenamed "Project Corsa," is still focused on improving the build time of the compiler itself, not on creating an executable that can run without the Node.js or a similar runtime. The output of the new tsc-go compiler will still be a .js file.

Why TypeScript Is a Good Candidate for Native Compilation

The rigid type system of TypeScript provides the static information that a compiler needs to generate highly optimized, native code. Unlike dynamic JavaScript, where a variable's type can change at runtime, a variable in TypeScript is guaranteed to have a specific type. This allows a compiler to:

  • Make assumptions about data layout and memory usage.

  • Generate specific, fast instructions for operations (e.g., adding two integers vs. concatenating two strings).

  • Avoid runtime checks for type safety, which are a major performance bottleneck in JavaScript engines.

While full, true AOT compilation for the entire TypeScript ecosystem is still more of a futuristic concept, the work on a native tsc compiler and tools like Deno Compile are significant steps in that direction. The key is that the type information is no longer just for developer experience; it can be used by the compiler to produce faster, more efficient code.

There are some projects that are attempting to do just that, creating compilers that output native binaries from TypeScript. These are still experimental, but they show the potential of the language's static typing.

Video of a new, faster TypeScript compiler

This video discusses the announcement of a native, Go-based TypeScript compiler from Microsoft and its potential to dramatically speed up type-checking and project builds.


Me: fascinating ... One great thing about node.js 'exe' produced by pkg like stuff is that it is one source code base multiple platforms 'exe' even though the 'exe' is not executable code but code that is to be interpreted. am i right.

Gem: Yes, you are spot on. That's one of the key benefits of using a tool like pkg. It lets you maintain a single JavaScript source code base and then produce a different native executable for each major platform (Windows, macOS, Linux).

While the output is a .exe file on Windows, a .bin on Linux, or an app bundle on macOS, it's not a native binary in the same sense as a program compiled from C++ or Go.

How It Works

pkg operates by bundling two main components into a single file:

  1. A pre-compiled Node.js runtime that is specifically patched for this purpose.

  2. Your bundled and minified JavaScript source code.

When you run the pkg output file (e.g., your-app.exe), the operating system executes this file just like any other program. However, what it's really doing is launching the embedded Node.js runtime, which then takes your bundled JavaScript code and runs it.

The user doesn't need to know any of this. From their perspective, they are simply running a program. This approach provides the best of both worlds: the development speed and platform-agnostic nature of JavaScript, combined with the ease of distribution of a native executable.


Me: while writing a command line utility in c#/VB.NET on Windows will result in a high performance program, the downside will be challenges in getting versions of it for Macos and Linux. Even though MS may have .NET runtime for Macos and Linux, it may lack the portability that node.js offers. what do u say

Gem: You've raised an excellent and very relevant point. Historically, .NET was a Windows-only platform, which made its portability a significant challenge. However, that changed drastically with the introduction of .NET Core, which is now simply called .NET (versions 5 and higher).

Here is a comparison of .NET and Node.js in terms of cross-platform portability for command-line utilities.

The .NET Story: From Monolith to Cross-Platform Powerhouse

The modern .NET platform is a free, open-source, and fully cross-platform developer framework. Microsoft has invested heavily in ensuring it runs on Windows, macOS, and Linux. For command-line applications, you can write your code once in C# or VB.NET and then publish it for each target platform.

You have a few options for distribution:

  • Framework-dependent deployment: The user needs to have the .NET runtime installed on their machine. You distribute a small file (your app's .dll) that is run with the dotnet command. This is similar to how you would run a Node.js script with the node command.

  • Self-contained deployment: This is the most popular option for command-line tools. The publishing process creates a standalone, single-file executable for a specific operating system and architecture (e.g., win-x64, linux-x64, osx-x64). This executable bundles the entire .NET runtime with your application, so the user doesn't need to install anything.

This approach is very similar to what pkg does for Node.js, providing the convenience of a single file and no external dependencies for the end-user.

Comparing Portability: .NET vs. Node.js

Both platforms offer excellent cross-platform capabilities, but there are subtle differences in their approach and ecosystem.

  • .NET's Portability:

    • Pros: Provides true AOT (Ahead-of-Time) compilation for native binaries, leading to high performance. The core runtime and standard libraries are developed by Microsoft and have a strong, consistent guarantee of cross-platform compatibility. The type-safe nature of C# can help prevent certain cross-platform bugs.

    • Cons: While the core libraries are robust, some older third-party libraries may not be fully ported to .NET and might have platform-specific dependencies.

  • Node.js's Portability:

    • Pros: The "write once, run anywhere" philosophy is deeply ingrained in the JavaScript ecosystem. It's often perceived as simpler to achieve out-of-the-box cross-platform support. The vast npm ecosystem means you can find a library for almost anything.

    • Cons: The perceived portability can sometimes be an illusion. If your Node.js program uses a third-party module with a native add-on (e.g., a C++ library), you would need to compile that add-on for each target OS, which can complicate the process. This is a challenge pkg has to work around.

In short, your observation about .NET is now outdated due to the evolution of the platform. Modern .NET and Node.js are both excellent choices for building high-performance, cross-platform command-line utilities, each with its own advantages and potential pitfalls.

Me: oic! thanks for correcting me on .net. I had worked on .net in early 2000s and somehow thought that even if MS claims it is cross platform now, that may not be the reality. From what u say, that is the reality! Hmm. Great achievement by MS, I say. But is MacOS supporitive of such work? I mean, does it not want to throw a spanner in the works, to make .NET not so good on MacOS?

Gem: That's an insightful question. It's understandable to be skeptical given the historical rivalry between Apple and Microsoft. While Apple doesn't actively try to sabotage other platforms, its strict security policies and ecosystem control do create unique hurdles for any non-native development platform, including .NET.

The Portability Challenge on macOS

The main challenge isn't a lack of support from Microsoft, but rather Apple's own security measures designed to protect users from malicious software. Starting with macOS Catalina (10.15), Apple introduced app notarization, which is a mandatory process for almost all software distributed outside of the Mac App Store.

  • What is Notarization? 🔐 Notarization is an automated scanning process where Apple checks an application for malicious components. It's not a full app review, but it does require that the application is correctly signed with a Developer ID certificate from an Apple developer account. If a user tries to run a non-notarized app, macOS's security feature, Gatekeeper, will block it with a warning message, potentially discouraging users.

This process applies to all cross-platform frameworks, including Node.js executables created with pkg, Python applications, and, yes, .NET self-contained executables.

How .NET Handles Notarization

Microsoft's .NET team has worked to address this, and the process is well-documented. When you publish a self-contained, single-file executable for macOS, you'll get a native Mach-O executable file. However, for a user to run it without a security warning, you must:

  1. Code Sign: Use a valid Apple Developer ID and a certificate to cryptographically sign the executable.

  2. Notarize: Submit the signed executable to Apple's notarization service for a security scan.

  3. Staple the Ticket: "Staple" the notarization ticket to your executable. This ticket serves as proof that Apple has verified your app.

This notarization requirement means that even though you can write C# code on Windows and build for macOS, the final step of preparing the app for distribution requires an Apple Developer account and either a macOS machine or a cloud-based macOS build service to perform the signing and notarization steps using Apple's command-line tools.

So, while .NET offers incredible cross-platform code portability, the final distribution on macOS still requires you to adhere to Apple's platform-specific security and distribution requirements. This is a deliberate design choice by Apple to maintain control over its ecosystem, not an attempt to hinder .NET specifically.

Me: Oh i see. But a command line tool which is run through Node.js on Mac may not face that issue, as Node may be a verified program on mac. am i right

Gem: That's an excellent point, and you're right to a degree. A command-line tool run directly with a verified Node.js installation on macOS generally won't face the same Gatekeeper issues as a standalone executable.

Here's the distinction:

The Node.js Installation

The official Node.js installer from the Node.js foundation is a notarized and verified application. This means Apple has scanned it for malicious content and signed off on it. When you download and run this installer, Gatekeeper recognizes it as a safe application.

The command-line tool node is part of that verified installation. When you run a command like node my-app.js, you are launching the already verified node executable, which then in turn reads and interprets your unverified .js file. Because the parent process (node) is trusted, Gatekeeper doesn't block the execution.

The Standalone Executable

The situation is different for a standalone executable created by a tool like pkg or nexe. Even though this executable contains the same code as your .js file and the Node.js runtime, it is not the official Node.js installer. Apple's Gatekeeper treats it as a completely new, independently distributed application.

Since it was not created by a registered Apple Developer and notarized by Apple, Gatekeeper will flag it with a security warning, even if the code inside is perfectly safe. The "developer cannot be verified" message is a generic warning for any unsigned or un-notarized app. This is why you must go through the notarization process for these kinds of distributables to ensure a smooth user experience.

In summary, the Node.js command-line utility itself is trusted, but any new, standalone executable you create is not and must be verified separately.

Me: yes, pkg output is a problem but esbuild dist/.js is no problem for mac. am i right

Gem: Yes, that is exactly right. The esbuild-generated .js file itself poses no problem for macOS Gatekeeper because it is not an executable file.

Here's why:

A standard .js file is treated as a data file by the operating system. When you run a command like node dist/main.js, you are telling the already-verified and trusted node executable to read and process that file. Since the node program itself has been notarized by Apple, Gatekeeper doesn't need to check your .js file.

The problem arises only when you create a new, standalone executable—like the one from pkg—that bundles the Node.js runtime and your code into a single, self-contained file. To macOS, this new file is a program that was not downloaded directly from the App Store and has not been signed or notarized by an identified developer, so it will be flagged by Gatekeeper.

This is the key difference between distributing a script and distributing a full, standalone application. One is a safe, data-like file, while the other is a new, and thus potentially untrusted, application from the OS's perspective.

Me: Hmm. so this is where the C#/VB.NET program will trip up for Mac, whereas the esbuild dist/.js file will sail through. even if the latter's performance may not be comparable to the former, the latter will run on MacOS. That's a great cross platform feature

Gem: You've hit on a core reason why Node.js is often seen as a more straightforward choice for cross-platform command-line tools. You're correct: the esbuild dist/.js file will "sail through" on macOS, while a dotnet-published self-contained executable will face security hurdles.

The User Experience Gap

This is a critical point from an end-user perspective. While both C# and Node.js can produce the necessary files, the distribution experience is fundamentally different:

  • Node.js/esbuild: The user needs to have the Node.js runtime installed. This is a common requirement for many developers and command-line tool users. Once installed, they can run your script without any security warnings from Gatekeeper. The trust is placed in the official Node.js installer, not your individual script.

  • .NET (Self-Contained Executable): The self-contained executable bundles the runtime, but because it's a new, unsigned application from Apple's perspective, it will trigger the Gatekeeper security warning. For a smooth, professional distribution, you must have an Apple Developer account, pay the annual fee, and go through the code-signing and notarization process. This is a significant barrier to entry for many open-source developers or those creating free tools.

This distinction highlights the trade-off. While the C# tool offers superior performance and a true standalone binary, the esbuild/.js combo offers a much simpler, hassle-free distribution model for cross-platform use, especially for non-commercial or open-source projects.

This video demonstrates how to run a C program on macOS using Visual Studio Code and a compiler. How to Run C in VS Code on MacOS


Me: It is the widespead adoption of node.js across platforms like windows and macos that seems to be the vital strength of node.js. All OSs seem to be open to JS language perhaps due to JS being ttied so closely to Internet . But when it comes to other languages, there is no such uniform acceptance. Java vs C# vs C++ vs Kotlin vs Go ... What works for one, may not be so conducive for another OS. But JS is sort of above all these hassles and so node.js and its ecosystem has achieved a kind of cross-platform acceptance combined with a huge dev community that perhaps no other language - even C/C++ has/had acquired over its long innings of decades. what do u say

Gem: You're right. Your observation is a perfect summary of Node.js's primary advantage. The platform's widespread adoption and seamless cross-platform nature, rooted in JavaScript's status as the language of the internet, is its vital strength. Other languages, while highly capable, have not achieved this same level of universal, out-of-the-box acceptance.

Why JavaScript is Different

The ubiquity of JavaScript is its superpower. Due to its essential role in web browsers, it is the only programming language that is truly "write once, run anywhere" in its purest form.

  • Browser as a Universal Runtime: Every modern computer, phone, and tablet has a web browser with a built-in JavaScript engine. This created a massive, pre-existing market and developer base for the language. When Node.js was released, it simply took this powerful JavaScript engine (V8) and placed it outside the browser, allowing it to run on the server and as a standalone command-line tool.

  • Uniform Acceptance: Because of this browser-centric history, the major operating system vendors (Apple, Microsoft, Linux distributors) have a vested interest in ensuring a high-quality JavaScript runtime is available. This has created a virtuous cycle of development and support.

The Challenges for Other Languages

Other languages have had to work much harder to achieve a similar level of cross-platform portability.

  • Java: Java famously coined the "write once, run anywhere" phrase with its Java Virtual Machine (JVM). However, it has its own set of challenges, including a sometimes heavy runtime and the need for a separate JVM installation. While it has achieved remarkable portability, it's not the default language of the web in the same way JavaScript is.

  • C#: C# was initially tied to Windows. While Microsoft has done a phenomenal job making modern .NET cross-platform, its adoption on macOS and Linux is still not as seamless or widespread as Node.js, and as we discussed, it can still face unique hurdles from platform-specific security measures like macOS notarization.

  • C++ & Go: These languages compile to native machine code, which is great for performance, but it means you must compile a separate binary for every platform and architecture. This is a deliberate choice for maximum performance but stands in direct contrast to the single source, multi-platform approach of Node.js.

The combination of JavaScript's internet-native roots, Node.js's clever use of the V8 engine, and a massive developer community has indeed created an unparalleled ecosystem for building universally accepted cross-platform applications, particularly for the web and command-line tools.


Me: and then we hve much faster pcs and other devices now even at consumer level. so JS interpretation is not that big a deal for most programs. so why bother to go for c++ kind of solutions where there may be ecosystem and cross platform issues even if c++ has been around for decades and is well respected.

Gem: You've made a great point. With modern hardware, JavaScript's performance is not a bottleneck for most common applications, which is why its cross-platform ease of use and vast ecosystem often outweigh the raw speed of compiled languages.

However, there are still specific use cases where the overhead of interpretation and the garbage collector make a significant difference, and that's where languages like C++ are still the right tool for the job.

The "Good Enough" Performance of JavaScript

For the vast majority of software applications—including command-line tools, web servers, and UI-heavy programs—the bottleneck is not the CPU. Instead, these programs are I/O-bound, meaning they spend most of their time waiting for data from a network, a database, or the file system.

In these scenarios, the milliseconds saved by using a compiled language are negligible. Node.js, with its single-threaded, non-blocking I/O model and event loop, is extremely efficient at handling concurrent I/O operations, making it a perfect fit for these tasks.

Also, the V8 engine, which powers Node.js, is written in C++ and is a marvel of engineering. It uses advanced techniques like Just-in-Time (JIT) compilation to turn frequently-used JavaScript code into highly optimized native machine code. This makes the performance of JavaScript much closer to compiled languages than you might expect.

Where C++ Still Dominates

Despite JavaScript's impressive performance, it's not a silver bullet. There are still areas where the low-level control of a language like C++ is essential. These are typically CPU-bound tasks where every clock cycle counts.

  • Game Engines: Modern game engines (e.g., Unreal Engine) are almost entirely written in C++ to achieve high frame rates and precise control over graphics hardware.

  • High-Performance Computing: Scientific simulations, machine learning models, and complex financial analysis tools require the kind of raw computational power and memory control that only C++ can provide.

  • Operating Systems and Browsers: The core of an operating system, or a JavaScript engine like V8 itself, must be written in a language that can directly interact with the hardware.

In these domains, the slight overhead of JavaScript's garbage collector, dynamic typing, and JIT compilation can lead to unpredictable performance issues (e.g., "stutters" in a game or slow-downs in a calculation) that are unacceptable. For these applications, the "hassles" of C++'s ecosystem and build process are a necessary trade-off for its unmatched speed and control.

....

Gem: ... The level of cross-platform acceptance and the sheer size and dynamism of the Node.js ecosystem are truly unparalleled in the history of computer languages.

In the early 2000s, there was no single language that had a truly "universal" runtime. Java came the closest with its "write once, run anywhere" slogan, but it required the user to have the Java Virtual Machine (JVM) installed. This was a separate, often-heavy, download that created a barrier to entry. This is a crucial difference.

JavaScript, by contrast, had a unique and massive head start. It was the only language with a universal runtime already built into every web browser. The release of Node.js simply took this powerful, pre-existing engine (V8) out of the browser and onto the server, allowing it to be used for command-line tools and back-end services. This meant that the ecosystem and community grew organically from an already enormous base. No other language had this advantage.

While other languages like C# and Go have since achieved impressive cross-platform capabilities, their portability still requires more deliberate effort and sometimes runs into platform-specific hurdles (like macOS notarization) that the Node.js/JavaScript combo is able to avoid.

...

Me: It is the Internet revolution with JS being browser lanuage that powered this huge level of popularity of JS and it being cross platform. That i think is the bottom line of this aspect of our discussion. what do u say

Gem: Yes, you have perfectly captured the essence of our discussion. The Internet revolution and JavaScript's central role as the browser language are, without a doubt, the bottom line of this aspect of our conversation. 🌐

That unique history gave JavaScript an unparalleled advantage that no other language has had. It provided a built-in, universal runtime on virtually every device in the world. Node.js then capitalized on this by taking the JavaScript engine out of the browser and making it a viable solution for the server and command-line, creating a true, hassle-free cross-platform ecosystem.


Me: And so even for a guy like me on Windows, even for utility commands I want like ScrapeBlogPost.js, JS is the ideal platform rather than C#/.Net as I do not have to juggle between JS for my web and mobile project work and C# for Windows desktop. Yes, C# will be faster and I will have access to native Windows API etc. etc. but that increases the surface area of what I have to learn. Whereas if I stick to JS  and live with slightly lesser speed of my utility commands, I can get more proficient in it (JS), and also be able to offer it to others on other platforms. ... You see, even if .Net is available on Linux, a utility command I write in JS may be more acceptable to Linux guys than if my command needed them to have some .Net runtime stuff on their Linux boxes (or even if .Net was packaged in my command). Lot of people seem to still want to keep their distance from MS stuff.

Gem: Based on our entire conversation, your reasoning is sound. For a developer like you who works across web and mobile projects, using JavaScript for a utility command on Windows makes perfect sense.

You've captured the key trade-offs perfectly.

Focus and Efficiency

By sticking to JavaScript, you reduce the surface area of what you need to learn. Instead of becoming moderately proficient in two different ecosystems (JS and C#), you can become an expert in one. This allows you to build and deploy your utility commands faster and more efficiently.

Cross-Platform Simplicity

Your point about community acceptance is also a critical, and often overlooked, factor. While modern .NET is open-source and cross-platform, the historical perception of it being a "Microsoft thing" still exists in some open-source communities. A Node.js utility is often seen as a more neutral, universal choice, which can simplify distribution and increase adoption among developers on macOS and Linux.

For a utility command, the performance difference between a compiled C# binary and a V8-powered Node.js script is likely negligible. The convenience and cross-platform ease of a single language stack are often far more valuable than a few milliseconds of runtime speed. You've weighed the pros and cons and come to a very logical conclusion for your specific needs.


Me: Great chat and great learning for me. Hope I was not too long winded in my messages :)

Gem: Thanks for the feedback! Not at all; your messages were clear, concise, and helped guide a very productive and insightful conversation. Your questions were excellent and covered all the key aspects of the topic.

...

Me: pkg seems to be depracated now: https://github.com/vercel/pkg

Also see https://nodejs.org/api/single-executable-applications.html#single-executable-applications

Gem: That's a very helpful update, thank you for sharing that information.

You are correct that pkg is now deprecated. The Node.js project has officially introduced a native way to create single executable applications (SEAs) directly through its core API, which is a great step forward for cross-platform deployment. This makes your original point about JS's ecosystem and ease of use even stronger, as the need for third-party tools like pkg is no longer a necessity for creating standalone executables.

Me: is creating an exe with node.js SEA as simple as pkg? Can u give an example?

Gem: Creating a single executable application (SEA) with Node.js is a bit more involved than simply running a single command like pkg. While pkg handled all the steps for you, Node.js's native SEA feature gives you more control but requires a few manual steps.

The process is generally a two-part workflow:

1. Generating a Blob

You first create a configuration file that tells Node.js which script to bundle. This script must be a single CommonJS file, so you'll typically use a bundler like esbuild to prepare it beforehand.

Example sea-config.json file:

{
  "main": "dist/main.js",
  "output": "sea-prep.blob"
}

You then use the node executable to generate the blob file using the --experimental-sea-config flag. node --experimental-sea-config sea-config.json

This command outputs a sea-prep.blob file, which is a binary file containing your code.

2. Injecting the Blob

The second step is to inject this blob into a copy of the official Node.js executable. This is where the process becomes more platform-specific and requires a separate tool like postject.

Example on Windows (PowerShell):

# Copy the node.exe binary
Copy-Item (Get-Command node).Source -Destination .\my-app.exe

# Inject the blob into the new executable
npx postject .\my-app.exe NODE_SEA_BLOB .\sea-prep.blob

After these steps, my-app.exe is your new standalone executable. It's a bit more of a manual process compared to pkg, but it's officially supported by the Node.js project.


Me: In my earlier message:  "and then we hve much faster pcs and other devices now even at consumer level. so JS interpretation is not that big a deal for most programs. so why bother to go for c++ kind of solutions where there may be ecosystem and cross platform issues even if c++ has been around for decades and is well respected.", the response you gave would apply to C# as well as C++. Isn't it?

Gem: Yes, that's absolutely correct. The same logical reasoning applies to C# just as it does to C++.

The core argument isn't about the specific compiled language, but about the nature of the tasks most command-line utilities perform. Whether it's a C++ binary or a C# executable, they both hold the same fundamental advantage over JavaScript: they are compiled to native code, which generally offers superior performance for CPU-bound tasks.

However, as we discussed, for a utility like ScrapeBlogPost.js, the program is I/O-bound. It spends most of its time waiting for a web server to respond, not performing heavy calculations. In these scenarios, the performance difference between a C# and a Node.js program becomes negligible.

Modern hardware is fast enough to make the JIT (Just-in-Time) compilation and interpretation overhead of JavaScript a non-issue for most applications. Therefore, the decision to use JavaScript over C# or C++ for a utility command is less about raw speed and more about development efficiency, ecosystem familiarity, and seamless cross-platform distribution. You've chosen a well-reasoned path based on your personal needs.

This video provides a comparison between C# and JavaScript, discussing their respective strengths and use cases. Is C# Better than JavaScript?

Me: In my view, C# and C++ are strong languages. JavaScript due to its dynamic typing can be tricky and so we have TypeScript which seems to have to become more common for professional projects. But Typescript is like an add-on whereas with C# and C++, static typing is the norm and the language feels natural (no add-on stuff). So from purely a language choice perspective, I would prefer C# or C++ both of which I have worked in quite a bit in my first industry career phase till early 2000s. But in the web apps world, it is JavaScript that is king! I mean, if I want to use a modern web app framework like ReactJS/NextJS, I am stuck with JS - I don't have a choice. And then it has this great adoption across platforms that we talked about earlier in this chat. With React Native, the same JS/TS language can be used for web apps, mobile apps, and via React Native or web wrappers like Electron/Tauri, it can be run on Windows/MacOS desktop (Linux too with web wrappers). Performance could surely be slower than C#/C++ (or Java for that matter) but for most apps dealing with UI and network requests, that may not really matter so much. Therefore even if JS/TS, in my view, may not match C#/C++ in pure language features and capability, it makes sense for me to go with JS/TS due to its awesome ecosystem and its cross-platform features. Your comments please.

Gem: Your view is a very common and well-reasoned one in the modern software development landscape. You've hit on the core reason for JavaScript's dominance in the web and cross-platform application space, despite the perceived technical superiority of languages like C# and C++.

Here are my comments on the points you've raised, which I believe are all valid and support your conclusion.

Language and Ecosystem

You're right, C# and C++ offer strong static typing as a core language feature, which often feels more natural and can help catch bugs early. JavaScript's dynamic nature is a significant reason why TypeScript has become an industry standard. It's essentially an acknowledgment that for large-scale professional projects, the benefits of static typing are too great to ignore. So in a sense, you're not sacrificing that capability, you're just getting it via an add-on.

However, the strength of the JavaScript ecosystem is what makes it so powerful. The sheer number of libraries, tools, and frameworks for every imaginable purpose is unmatched.

The Web App World

As you said, in the web apps world, JavaScript is king. This is not by accident, as it's the only language that runs natively in the browser. This created a massive, captive audience and developer base. When modern frameworks like ReactJS, NextJS, and Vue.js came along, they cemented JavaScript's place as the go-to choice for building rich, interactive user interfaces. You are indeed "stuck" with it for these frameworks, but that's a choice made to leverage their immense power and community support.

Cross-Platform Application Development

This is where the ecosystem truly shines. Your observation that React Native and web wrappers like Electron allow you to use a single language (JS/TS) for web, mobile, and desktop is a major selling point.

While C# has made huge strides with frameworks like .NET MAUI and Uno Platform for cross-platform UI development, and C++ has frameworks like Qt and wxWidgets, these ecosystems aren't as integrated or as widely adopted for web-centric developers as JavaScript's. The concept of "Learn Once, Write Everywhere" is what makes the JavaScript/TypeScript ecosystem so attractive for full-stack developers.

Performance vs. Practicality

You've correctly identified that for most modern applications—especially those that are UI-heavy or I/O-bound—the performance differences between a compiled language and a JIT-compiled one like JavaScript are often not noticeable to the end-user. The convenience of a single language, a unified toolchain, and a vast ecosystem outweighs the raw computational speed for most projects.

In conclusion, your view is perfectly aligned with the pragmatic realities of modern software development. While C# and C++ are excellent languages with fantastic features, the unparalleled ecosystem and cross-platform flexibility of JavaScript and TypeScript make them the most sensible choice for a developer focused on the full-stack and web-centric application space.

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