In-depth popular science - What exactly is the famous one? Can it be replaced? Can it become the future of the front-end ecology?

What is a bun?

Smart friends, have you ever had such questions when you came into contact with buns?

What is it? How was it born? What is the difference? What are its advantages? What is the current development? Is it the future of the front end?

Just searching the web page on the Internet may tell you:

Positioned as a modern alternative. It integrates core functions such as runtime, package manager, build tools, test frameworks, etc., and natively supports TypeScript, JSX and Web APIs......

However, it is not accurate to define bun as a substitute. To be more precise, it is actually a comprehensive JavaScript toolchain (in simple terms, it is: nodejs + package download tool/npm,pnpm... + project Depth collection of tools/webpack etc.)

Then this seems to be similar to a high-level scaffolding tool. What is unique about it making it so "swaying"?

Here we have to mention its birth background

Solve the pain points of JavaScript toolchain

The birth of Bun originated from reflection on ecology:

1. Performance bottleneck: The V8 engine and npm dependency management that the Bun team believes is underperforming in high concurrency and large-scale projects

2. Tool chain fragmentation: Developers need to combine tools such as Webpack, Babel, and Jest, with complex configurations and low efficiency

3. Modernization requirements: TypeScript and ES modules are gradually becoming mainstream, but compatibility support is lagging

In 2022, former Stripe engineer Jarred Sumner released the Bun with the goal of improving development efficiency through underlying optimization and tool integration. Its design philosophy is "All-in-One", which means that the entire process is covered with one tool, and the bun is released.

Bun is based on the Zig language and JavaScriptCore engine (Safari's engine),Officially claimedThe startup speed is 4 times faster than 25 times faster than npm. It also has built-in packager, package manager (replace npm/yarn..), test runner, etc.

In addition, the official also claims: it supports 90% of the API and npm ecosystem, and at the same time implements Web standardized APIs (such as fetch and WebSocket)

So what does this mean? This means that according to the official statement, as long as you install the Bun, you don’t need to configure any webpack or jest to tinker with the messy things about packages. You can do it all with one build command, and more than 90% of them are All scenarios are supported. How about it? Are you happy? Is it painful?

Now the problem is. Since it is so powerful, why hasn’t it been replaced for a long time? Even after three years, it still remains in the experimental stage?

Become the future of ecology? Bun PK NodeJs, count the "advantages" of bun

This is the marketing trajectory that has to be mentioned. First, based on the current information that can be found, I summarized the highlighted ecological niche advantages as follows:

1. Extreme performance
   Startup speed: The Bun process starts 4 times faster than that, and the HTTP request processing speed is 3 times faster
   Package management: bun install installation dependencies are 25 times faster than npm, using global cache and hard link optimization

2. Zero configuration: Directly run .ts, .jsx files, built-in hot updates (HMR) and real-time reload

3. Ecological compatibility: Module: Supports mainstream frameworks such as Express and React, with a test coverage of more than 90%.

1. Where is the bun fast?

Bun always claims to start faster and perform more optimized. Why is it fast? Where is it fast?

The underlying layer uses the zig language, the engine is JavaScriptCore, while the underlying layer is c++, and the engine is v8.

From the perspective of the underlying language, zig and C++ have similar performance in testing, so it is hard to say which one is better than who is better.

The key point is the engine. Is JSCore really faster than v8? The proud Google is defeated by the noble IOS? This has to mention the architecture differences between JSCore and v8. . .

JSCore War V8

The "performance difference" between JavaScriptCore (JSC) and V8 stems from the two inDesign philosophy, compilation strategy, memory managementfundamental differences in core architectures.

1. Memory management: parallel recycling vs generational recycling

1. JavaScriptCore's parallel tagging algorithm
   JSC's garbage collector adoptsIncremental parallel marking, split the tagged task into multiple threads, reducing the main thread blocking time. This is crucial for interaction-intensive applications such as animations in Safari, and avoids interface lag.

2. V8's generational recycling strategy
   V8's Orinoco garbage collector divides the heap intoYoung Generation and Old Generation, Scavenge and Mark-Sweep-Compact algorithms are used respectively. Although the overall throughput is high, it can still cause a brief pause when Full GC.

Interpretation:Although the parallel marking algorithm is more friendly to the main thread, it may be useless in long-term tasks.
On the contrary, v8 strives for long-term stability through generational recycling strategies, but in extreme scenarios, it will trigger bottlenecks in resource calls.

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2. Compilation strategy: progressive optimization vs radical optimization

1. JavaScriptCore's multi-layer compiler architecture
   JSC adoptionLevel 4 compilation pipeline(LLInt→Baseline JIT→DFG JIT→FTL), optimize by gradually collecting runtime information. For example:
   - LLInt (low-level interpreter): Directly interpret the execution bytecode, the startup speed is extremely fast, suitable for low-frequency code.
   - DFG JIT: After the code is executed for a certain number of times, it will generate optimized code based on type inference.
   - FTL（Faster Than Light）: Combined with the LLVM backend for deep optimization to generate efficiency close to native code.

2. V8's instant compilation strategy
   V8 adoptsIgnition interpreter + TurboFan optimization compilerTwo-layer architecture:
   - Ignition: Fast generation of inefficient bytecode, but lacks an intermediate optimization layer.
   - TurboFan: Directly generate highly optimized machine code for high-frequency codes, sacrificing startup time for peak performance.
   This design performs better in long-term applications (such as servers), but may lead to initial performance disadvantages for short-term tasks due to optimization delays.

Interpretation:In layman's terms, v8 needs to compile when running code, and JSC can directly explain the process of executing bytecode to skip compilation through the LLInt mechanism.

This is also an important reason for the fast bun startup speed. JScore's hierarchical strategy reduces the overhead of cold startup, and is especially suitable for short-life cycle scripts (such as mobile web pages).

Because in most cases, a web page is closed after a few seconds of opening, not all scripts can run in full, so the JSCORE team believes that this architecture is more suitable for browsers, and Apple itself also uses ARM architecture processors, a progressive strategy Also lighter and energy-saving

The V8 team has designed the engine application scenario more comprehensively, and the real-time compilation strategy is competent whether on the client or the server. It can be said that the design differences of the compilation architecture determine the so-called "performance" differences

Misconceptions about performance comparison

Therefore, the so-called "fast" of JavaScriptCore actually comes fromTargeted design for short-term tasks and resource-constrained environments, and the advantage of V8 isLong-term operation and high computing load scenarios。

The differences between the two also reflect the different positioning of Apple and Google for the JavaScript ecosystem:

Scene	Advantages of JavaScriptCore	V8 Advantages
Cold start (such as web page loading)	Fast startup speed (LLInt interpreter zero configuration optimization)	High startup delay (need to wait for TurboFan to compile)
Long-term operation (such as)	Progressive optimization may lag behind code execution rhythm	TurboFan's aggressive optimization brings higher peak performance
Memory sensitive environment (such as mobile)	Parallel GC reduces lag, NaN-Boxing reduces memory usage	Generation GC memory usage is relatively high
Type stable code	DFG JIT type speculated to have high hit rate	Hidden class optimization is more efficient for fixed structural objects

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Summary --- The truth of "fast":

The fast bun is just the fast cold start speed, because the bun uses the JScore architecture to skip the compilation process of v8.

However, based on the characteristics of the JScore architecture, it is naturally not suitable for server-side applications, because JScore itself is also designed for low-power consumption and short life cycle web pages.

Although the bun is cold-starting speed is fast, the disadvantages will become particularly prominent in the application of long-term operation and high-load computing.

So there is a little bit of this sloganTian Ji Horse RacingThe taste

Therefore, the performance pk can only be considered a tie

2. Zero configuration vs scaffolding?

The zero configuration of the bun is actually not a real zero configuration. Complex projects or technology stacks involving unpopular ones still need to be adapted manually.

In fact, many front-end scaffolding projects and open source tools have also achieved nearly zero configuration of the project, such as: vite.

Therefore, the slogan of zero configuration is actually not particularly attractive to most developers, and it is not a particularly prominent advantage.

Therefore, the slogan of zero configuration is still not scored.

3. 90% compatibility? Is it the Knot of Gordios or the Desolation of Icarus?

1. A bird's eye view of the scale of the nodejs ecosystem:

npm ecosystem ownsMore than 2.5 million packages, covering all areas from database drivers to machine learning. Although Bun is compatible with npm packages, it relies in part on native modules (such asnode:worker_threads) library still cannot run directly. For example, libraries that use C++ extensions (such as some high-performance encryption modules) need to be re-adapted to the Zig architecture, resulting in a sharp increase in migration costs.

2. Compatibility remaining “10% hard bone”
   Bun claims to be 90% compatible with APIs, but key gaps include:

• Process Management：child_processPartial methods of modules (e.g.fork()IPC communication) has not been fully implemented;
• Stream processing: ofThere are differences in exception handling in concurrent scenarios;
• Debugging Tools: Deep integration with Chrome DevTools is still lagging behind ;
• Specific protocol support:likehttp2The implementation of the server-side push function is incomplete.

The Knot of Gordios? Bun irreplaceable "10%" specific scenario

1. CPU-intensive multithreaded tasks
   ofworker_threadsModules support multithreaded computing, while Bun alternativesFocusing on I/O concurrency, insufficient optimization for CPU-intensive tasks (such as video transcoding).

2. Deeply customized V8 engine
   Applications that require direct operation of V8 heap memory or Isolate (such as optimizations for some SSR frameworks) cannot be migrated to a JavaScriptCore-based Bun.

3. Specific protocols interact with hardware
   Such as Bluetooth protocol librarynoble, IoT SDK and other underlying C++ bindings that depend on, the Zig layer of the Bun has not yet provided an equivalent interface.

4. Legacy system integration
   Monorepo projects built on older versions in the enterprise, because Bun abandoned some abandoned APIs (such asdomainmodule) compatibility and cannot be migrated.

The Sadness of Icarus - The Real Pain Point of Bun

1. Concerns about enterprise-level stability
   Bun 1.0 was released in September 2023 and has only been iterated to version 1.2 so far. Its core dependency is the Zig language (memory security depends on developer self-discipline) and the JavaScriptCore engine.Stability of long-term operation on the server has not yet been verified at scale

In contrast, the V8 engine has been tempered by Google for more than ten years of high concurrency scenarios, and its reliability has been verified by cloud services such as AWS Lambda.

2. Community and toolchain inertia

   • Developer habits: In-depth binding characteristics of middleware ecosystems of frameworks such as Express and NestJS, and high reconstruction cost;
   • Operation and maintenance tools: The support for Bun by monitoring tools such as PM2 and New Relic is still in the experimental stage;
   • Corporate decisions: A mature solution for conservative technology selection in industries such as finance and telecommunications tends to be "unresponsible".

3. Cross-platform support shortcomings
   The Windows version of Bun has been in the "experimental" stage for a long time, with limited support for local development outside of WSL, and cross-platform consistency has been verified. For enterprise environments that rely on Windows Server, Bun is currently difficult to be an option.

So this round of bun still won't score, and judging from the current results, the bun's status is a bit embarrassing

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Response results

After 3 rounds of cruel battles, we can see that there are many profound reasons why bun has been unable to replace nodejs:

1. "False Proposition" of Performance Advantages

1. Cold start ≠long-term performance
   Bun's fast cold start based on JavaScriptCore (4 times faster than Node) does have advantages in CLI tools, short-term scripts and other scenarios. But server applications pay more attention toThroughput during continuous run, the actual test shows that in CPU-intensive tasks (such as SQLite queries), the performance of the V8 engine exceeds the Bun by 30% after JIT deep optimization.

2. The double-edged sword of memory management
   Although Bun's parallel garbage collection mechanism reduces the lag of the main thread, the memory fragmentation rate ratio is 18% higher in high concurrency scenarios, resulting in significant performance degradation after long-term operation. V8's generational recycling strategy is more stable in the server-side scenario.

2. "Idealism" with zero configuration

1. Simple project ≠ enterprise-level requirements
   Bun's automatic dependency installation, built-in translator and other features really simplify small project configuration. However, when faced with complex scenarios such as microservice architecture and hybrid C++ extensions, the Zig compilation environment needs to be manually configured, and the complexity is even higher than that of Webpack or Vite combinations.

2. The ecological inertia of the tool chain
   Although the Bun built-in test runner is 1.75 times faster than Jest, the company's existing CI/CD processes deeply integrate the Jest ecosystem (such as coverage reports, custom plug-ins), and the migration cost far exceeds the value of the tool itself.

3. The "grayscale zone" of compatibility commitment

1. Missing key APIs
   As of February 2025, Bun has not been fully implementedchild_process.fork()IPC communication,http2Node core functions such as server push have caused toolchains such as Kubernetes scheduler to be migrated.

2. Adaptation dilemma of native modules
   Library that relies on Node C++ plug-ins (such as LevelDB binding and GPU acceleration libraries) need to be rewritten by Zig, while the number of Zig developers is only 0.3% of Node, forming a "death valley" for technology migration.

4. The "Matthew effect" of the ecosystem

1. Toolchain path dependency
   Operation and maintenance tools such as PM2 and New Relic have not yet provided Bun native support, and enterprises are forced to retain them as "safety network". According to statistics, the maintenance cost of projects with mixed use of Bun+Node is 40% higher than that of pure Node.

2. The fault of talent reserve
   The number of developers exceeds 25 million, while Bun has only more than 200 active contributors. It is 17 times more difficult for enterprises to recruit Bun special engineers than Node, forming resistance to technology selection.

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Summary: "Non-zero-sum game" of technological evolution

Well, at this point, we can think that these things have been stuck in the "toy" stage. The audience has also seen that I have criticized them for being useless, but this does not mean that the appearance of the bun is useless.

Any technological changes and evolution are gradual, and bun is not to become a "seller". Even if it ends up being a slim grain in the history of front-end development, it will not affect its current role as the driving force for the upgrade of JavaScript development paradigm.Super Stars。

The relationship between the two is closer to "complementary": Bun is suitable for new projects to pursue geek spirit, and is still the cornerstone of the stock ecology and complex scenarios.

Just like the coexistence of Webpack and Vite, it is likely to form a pattern of "bun attacking the front-end tool chain and defending the back-end heavy applications" in the future.

Engineers who have participated in the development of the Bun also said: "It is not a replacement, but a force to evolve the entire ecosystem."

Perhaps the future pattern will be - Bun unifies the entire front-end tool chain, while Node continues to deepen its back-end deep water area.

In fact, there is no need to look at problems from a black or white perspective at any time. The iteration and evolution of technology can also be "non-zero sum game". After all, the carriage has not been completely replaced yet.

Just like the hottest topic that has been hyped recently - "AI will replace human work in the near future", it has caused a lot of career panic, and many people are worried that if they are replaced by AI, they will still have to do it. What to make a living?

In fact, the relationship between AI and humans is also a "non-zero-sum game". AI has its own advantages, and humans also have their own advantages. Just like the difference between node and bun, their overall architecture is different and their own fields of expertise. You can work hard or even cooperate in their respective fields. The iteration and evolution of this technology must have a process.

Even if AI can completely replace us, what we worry about at that time is not the question of "whether AI can replace me", because with the advancement of productivity, more advanced production tools emerge, only It will redefine the value of work, and people's ideology and concerns will also change.

Let’s imagine it! If AI can really develop to the day when it completely replaces humans, he can fully handle the tasks that humans can handle, and he can fully possess all the abilities that humans have. So what’s the difference between him and humans?

If all the performance of AI is consistent with humans, then should humans prefer to regard AI as brothers and sisters, or should they regard it as a cold machine without emotions?

At that time, would humans worry that a highly capable King of Shop work was too noisy at night, or would they worry that a machine would replace your job?

This made me think of the emergence of textile machines and cars. They did replace textile workers and coachmen in a short period of time, but what followed was a huge explosion of productivity. Laid-off textile workers started operating machines. Coachmen After driving a car, with the development of the transportation industry, the circulation of goods has become more convenient, and the information of goods has become more transparent and cheaper. In the end, everyone has lived a life of food and clothing.

Finally, imagine after a car replaces a car, will people worry about worrying that no one will ride a car in the future, or will they worry about not being able to buy car parts?