Deno 対 Node: JavaScript の次の進化、しかし準備はできていますか?

There's no doubt that Node.js is the most popular and widely used JavaScript runtime environment today. However, with the release of Deno in 2018, the development community was introduced to a new, more secure, and modern alternative to Node.js. Created by the same developer, Ryan Dahl, Deno was designed to address several shortcomings in Node.js. The big question is: Can Deno replace Node.js as the go-to JavaScript runtime? Despite the excitement surrounding Deno’s introduction, its adoption has been slow, and Node.js remains dominant.

In this article, we will explore why developers continue to favor Node.js over Deno, despite Deno’s modern design and security features. We’ll also compare the two platforms across several critical areas.

What is Node.js?

• Node.js is an open-source, cross-platform, server-side JavaScript runtime environment built on Google’s V8 JavaScript engine. Released in 2009, Node.js has revolutionized web development by allowing JavaScript to be used on the server side.
• Node.js employs a single-threaded, non-blocking, event-driven architecture, making it ideal for building scalable, data-intensive, real-time applications that run across distributed devices. Its strength lies in its ability to handle thousands of connections concurrently with minimal memory consumption, using callback functions for non-blocking I/O operations.
• Node.js has grown into a robust ecosystem supported by npm, a vast package manager that allows developers to easily share and reuse code. This ecosystem is one of the key factors in Node’s enduring popularity.

What is Deno?

Deno is a modern runtime for JavaScript, TypeScript, and WebAssembly, designed by Ryan Dahl in 2018 to address some of the design flaws he identified in Node.js. These include:

1. A poorly designed module system relying on centralized distribution (npm).
2. Unstable legacy APIs.
3. A lack of security controls.

Deno aims to fix these issues by offering a more secure and developer-friendly experience. It's built with the following goals in mind:

• Security: Deno runs scripts in a sandboxed environment, meaning they have no file system, network, or environment access unless explicitly granted.
• TypeScript support: Deno has built-in TypeScript support, allowing developers to write TypeScript without any additional configuration.
• Modern API: Deno adopts modern web platform standards, using features like fetch and Web Workers that are consistent with browser APIs.
• Single executable: Deno is distributed as a single binary, making it simple to set up and use.

Deno vs. Node.js: Key Differences

1. Module Management

• Node.js: Node relies on npm (Node Package Manager) for third-party modules, and its dependency management system is centered around package.json and the node_modules folder. This centralized ecosystem has led to the creation of millions of modules that can be easily reused by developers.
• Deno: In contrast, Deno has no centralized package manager like npm. Instead, it allows developers to import modules directly from URLs, such as GitHub or a CDN:

import { serve } from "https://deno.land/std@0.145.0/http/server.ts";

While this is more flexible, it also poses potential security risks if third-party URLs are compromised. However, Deno mitigates this with caching mechanisms that prevent re-downloading unless necessary.

2. Security

One of the key features that differentiate Deno from Node.js is its secure-by-default design.

• Node.js: In Node, scripts have full access to the file system, network, and environment variables by default. This openness can lead to vulnerabilities if not handled carefully, as third-party libraries can introduce malicious behavior.
• Deno: Deno enforces strict security controls, only granting permissions if explicitly allowed via command-line flags. For example, to allow Deno to read the file system:

deno run --allow-read app.ts

You can grant fine-grained permissions for file access, network requests, and environment variables, making Deno a more secure environment by default.

3. TypeScript Support

• Node.js: While Node doesn’t have native TypeScript support, developers can install the TypeScript package and configure it manually:

npm install -g typescript
tsc --init

Developers need to transpile TypeScript to JavaScript before running it in Node.js, which can slow down development workflows.

• Deno: Deno has built-in TypeScript support, allowing you to execute TypeScript files directly without any configuration:

deno run app.ts

This makes Deno an attractive option for developers who prefer TypeScript, as it eliminates extra setup and reduces friction.

4. APIs and Callbacks

• Node.js: Node’s early APIs were based on callback functions, which often resulted in callback hell. While the introduction of Promises and async/await in JavaScript has improved the situation, many legacy Node APIs still rely on callbacks.

fs.readFile('file.txt', (err, data) => {
  if (err) throw err;
  console.log(data);
});

• Deno: Deno was designed with modern JavaScript features in mind and supports async/await out of the box. Deno’s APIs are promise-based by default, eliminating the need for callback-based patterns:

const data = await Deno.readTextFile("file.txt");
console.log(data);

5. Performance

Both Deno and Node.js are built on Google’s V8 JavaScript engine, so their performance characteristics are quite similar. However, Deno has a smaller memory footprint due to its more modern design.

• Node.js: Node.js is optimized for handling asynchronous I/O tasks efficiently. It excels at serving many concurrent connections with minimal memory overhead.
• Deno: Deno’s modern architecture and reliance on Rust and Tokio for asynchronous tasks make it highly performant, although large-scale benchmarks between Node.js and Deno are still evolving.

Why Developers Stick with Node.js
Despite Deno’s improvements over Node.js, the transition to Deno has been slow. The reasons are largely practical:

• Mature Ecosystem: Node.js has been around since 2009 and has built a massive community and ecosystem of libraries, packages, and tooling. Developers have years of experience with Node.js, and the learning curve to switch to Deno is a significant barrier.
• npm: The Node Package Manager (npm) is a massive repository of reusable code, making it easy to find libraries and packages for nearly any functionality. Deno's module system, while innovative, lacks the centralized management and community adoption of npm.
• Backward Compatibility: Many production systems today rely on Node.js. Migrating to Deno would require rewriting or refactoring significant portions of code, which may not justify the effort for most companies.
• Familiarity: Developers are familiar with the workflow, tools, and deployment processes in Node.js. Switching to a new runtime like Deno introduces uncertainty and risk, which many teams are hesitant to embrace.

Conclusion

Deno undoubtedly offers a modern, secure, and developer-friendly environment, but Node.js continues to dominate due to its mature ecosystem, vast library support, and widespread adoption. While Deno addresses some key issues with Node, such as security and modularity, it’s still an evolving platform.

For developers who need stability, a large community, and a wealth of third-party libraries, Node.js remains the preferred choice. However, as Deno matures and gains more traction, it could become a viable alternative, especially for projects that prioritize security and TypeScript support out of the box.

Ultimately, the choice between Deno and Node.js depends on your project’s specific needs. If you're building a greenfield project with a focus on security and modern JavaScript features, Deno is worth considering. For legacy applications or projects that rely on a large ecosystem of modules, Node.js still reigns supreme.

Thank you for reading!

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