npm 與yarn：主要差異與深入比較

在 JavaScript 生態系統中，選擇 npm 與 YARN 作為套件管理器可以顯著影響您的開發工作流程。 npm 和yarn 都是廣泛使用的工具，可協助開發人員管理專案中的依賴項，但每種工具都提供獨特的功能來滿足不同的專案需求。 npm 與yarn 的深入比較涵蓋了它們的主要差異、優勢和用例，可協助您為專案做出明智的決策。

1. 安裝及依賴解析

新專案管理

npm 按順序安裝依賴項並在 node_modules 資料夾中建立巢狀結構，這可能會導致安裝時間更長並可能導致依賴項重複。看起來像這樣：

project/
├── node_modules/
│   ├── package-a/
│   │   └── node_modules/
│   │       └── package-b/
│   └── package-c/

優點：

• 熟悉程度： npm 預先安裝了 Node.js，使其成為許多開發人員的預設套件管理器。
• 廣泛的兼容性： 透過 npm 龐大的生態系統，大多數 JavaScript 專案無需額外設定即可無縫運作。

缺點：

• 效能：順序安裝可能會導致安裝速度變慢，尤其是對於大型專案。
• 巢狀依賴項：依賴項的深度巢狀可能會導致 node_modules 資料夾臃腫，有時會導致限制目錄深度的檔案系統問題。

紗

Yarn 透過使用並行安裝改進了 npm 的安裝過程，從而創建了扁平結構：

project/
├── node_modules/
│   ├── package-a/
│   ├── package-b/
│   └── package-c/

優點：

• 速度： Yarn 的平行安裝通常比 npm 快 2-3 倍，這對於具有許多依賴項的專案來說非常有效率。
• 扁平結構：扁平資料夾結構可防止深層巢狀問題，並最大限度地降低依賴衝突的風險。

缺點：

• 額外設定： Yarn 需要與 Node.js 分開安裝，這為新使用者增加了額外的步驟。
• 小型項目的開銷：對於小型項目，yarn 的效能提升可能不那麼明顯，這使得 npm 成為更簡單的選擇。

2. 鎖定檔案和確定性構建

npm：package-lock.json

npm 使用 package-lock.json 檔案來鎖定依賴版本，確保跨環境安裝一致：

{
  "name": "project",
  "version": "1.0.0",
  "dependencies": {
    "lodash": "^4.17.21"
  }
}

優點：

• 自動生成： package-lock.json 檔案自動生成，有助於確保在所有環境中安裝相同版本的依賴項。
• 向後相容性： 確保較舊的 npm 版本仍然可以正常運行，保持相容性。

缺點：

• 使用不一致（舊版）：在舊版的 npm 中，預設並非總是使用 package-lock.json 文件，這可能會導致安裝不一致。

紗線：紗線.lock

Yarn 的yarn.lock 具有相同的用途，但始終預設產生並使用，以確保更具確定性的建置：

# yarn lockfile v1

lodash@^4.17.21:
  version "4.17.21"
  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz"
  integrity sha512-v2kDEe57lec...

優點：

• 預設確定性： Yarn 的yarn.lock 檔案保證在所有環境中安裝一致。
• 總是使用： 與 npm 不同，yarn.lock 檔案始終被使用，確保每次安裝都是相同的。

缺點：

• 簡單專案的開銷： 鎖定檔案的嚴格性可能感覺像是較小或不太複雜的專案的開銷。

3. 安全特性

新專案管理

npm 提供了一個內建的 npm 審計命令，透過掃描 npm 安全諮詢資料庫來檢查專案依賴項中的漏洞：

npm audit

Pros:

• Easily Accessible: The audit feature is integrated into npm, offering developers a quick way to check for security issues.
• Large Database: npm has a vast security advisory database due to its large user base, covering many known vulnerabilities.

Cons:

• Less Detailed Reports: The npm audit command may not provide as detailed or actionable feedback as developers expect.

yarn

Yarn also has an audit command but goes further by verifying package integrity during installation. Yarn 2+ introduced "Zero-Installs," allowing projects to skip installs entirely, reducing the risk of security issues when fetching dependencies.

yarn audit

Pros:

• More Proactive: Yarn not only checks for known vulnerabilities but also validates the integrity of every package during installation.
• Zero-Installs: This feature adds another layer of security by enabling projects to be cloned and used without running yarn install, reducing potential risks.

Cons:

• Setup Complexity: For Yarn’s more advanced security features like Zero-Installs, developers need to adopt Yarn 2+, which can require additional setup and configuration.

4. Workspaces and Monorepo Support

npm Workspaces

npm introduced workspaces in version 7, allowing developers to manage multiple packages within the same project. This feature is particularly useful in monorepos, where several related packages are maintained together.

{
  "name": "my-project",
  "workspaces": [
    "packages/*"
  ]
}

Pros:

• Official Support: npm’s native workspace support simplifies dependency management in monorepos.
• Familiarity: npm workspaces follow the same conventions as other npm functionality, so it’s easy to integrate into existing workflows.

Cons:

• Newer Feature: npm’s workspace implementation is relatively new and may not be as fully-featured as yarn’s.

yarn Workspaces

Yarn has supported workspaces for much longer and is generally considered more feature-rich for handling monorepos. Yarn’s workspace feature allows for more granular control over dependencies in monorepos.

{
  "private": true,
  "workspaces": [
    "packages/*"
  ]
}

Pros:

• Mature Feature: Yarn’s workspaces are more robust and offer additional commands for managing multiple packages.
• Better for Large Monorepos: Yarn is generally considered the better choice for larger or more complex monorepos due to its mature implementation.

Cons:

• Learning Curve: For developers new to monorepos or Yarn’s workspace management, there may be a steeper learning curve.

5. CLI Commands and Usability

npm

npm offers a variety of commands for managing dependencies:

npm install <package>
npm uninstall <package>
npm update
npm run <script>
</script></package></package>

Pros:

• Consistency: As the default package manager for Node.js, npm’s commands are familiar and widely used.
• Extensive Documentation: npm's extensive community and documentation make it easier for developers to find solutions to common issues.

Cons:

• Verbosity: npm commands can be more verbose and less intuitive compared to yarn. For example, npm install versus yarn’s simpler yarn add .
• Fewer Utility Commands: While npm covers the basics, it lacks some of the utility commands yarn provides, such as yarn why for checking package dependencies.

yarn

Yarn offers similar commands but with shorter and more intuitive syntax:

yarn add <package>
yarn remove <package>
yarn upgrade
yarn <script>
</script></package></package>

Pros:

• Simplicity: Yarn commands are often shorter and more intuitive. For example, yarn replaces npm install, and yarn <script> replaces npm run <script>.</script>
• Additional Features: Yarn provides extra utility commands like yarn why, which shows why a package was installed and which dependencies rely on it.

Cons:

• Learning Curve: Developers accustomed to npm might find the transition to yarn’s command set slightly confusing at first, particularly with yarn-specific commands.
• Less Ubiquity: While yarn has many useful features, it’s not as universally used as npm, meaning there may be fewer resources or support in certain cases.

6. Offline Mode and Caching

npm

npm has basic offline capabilities, allowing you to install packages from the cache if they were previously installed:

npm install --offline

Pros:

• Improved Offline Support: Recent versions of npm have made improvements to offline support, but it's still limited.

Cons:

• Less Reliable: npm’s offline capabilities aren’t as comprehensive as yarn’s, especially in environments with limited internet access.

yarn

Yarn’s offline support is more robust, allowing you to work completely offline as long as the dependencies have been previously installed.

yarn install --offline

Pros:

• Reliable Offline Mode: Yarn stores a more comprehensive cache, ensuring that all necessary files are available when offline.
• Ideal for CI/CD: Yarn’s offline capabilities significantly improve CI/CD pipeline performance by reducing the need for internet access.

Cons:

• Initial Setup: Yarn’s offline support requires an initial installation before it can fully function offline.

Conclusion: npm vs yarn

In summary, the choice between npm vs yarn comes down to the needs of your project:

• npm is the default and most familiar option. It’s well-suited for small to medium projects and offers solid features like npm audit and workspace support. If your project is relatively simple, npm is likely sufficient for your needs.
• yarn shines in larger projects or complex monorepos where speed, deterministic installs, and robust offline support are crucial. Yarn’s parallel installation, enhanced security features, and advanced workspace management make it the better choice for teams working on large-scale projects.

When comparing npm vs yarn, consider your project’s size, complexity, and need for features like workspaces and offline support. Both are excellent tools, but your decision should align with your workflow and project requirements.

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