npm 与yarn：主要区别和深入比较

在 JavaScript 生态系统中，选择 npm 与 YARN 作为包管理器可以显着影响您的开发工作流程。 npm 和yarn 都是广泛使用的工具，可帮助开发人员管理项目中的依赖项，但每种工具都提供独特的功能来满足不同的项目需求。 npm 与yarn 的深入比较涵盖了它们的主要差异、优势和用例，可帮助您为项目做出明智的决策。

1. 安装及依赖解析

新项目管理

npm 按顺序安装依赖项并在 node_modules 文件夹中创建嵌套结构，这可能会导致安装时间更长并可能导致依赖项重复。看起来像这样：

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

优点：

• 熟悉程度： npm 预装了 Node.js，使其成为许多开发人员的默认包管理器。
• 广泛的兼容性： 借助 npm 庞大的生态系统，大多数 JavaScript 项目无需额外设置即可无缝运行。

缺点：

• 性能：顺序安装可能会导致安装速度变慢，尤其是对于大型项目。
• 嵌套依赖项：依赖项的深度嵌套可能会导致 node_modules 文件夹臃肿，有时会导致限制目录深度的文件系统问题。

纱

Yarn 通过使用并行安装改进了 npm 的安装过程，从而创建了扁平结构：

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

优点：

• 速度： Yarn 的并行安装通常比 npm 快 2-3 倍，这对于具有许多依赖项的项目来说非常高效。
• 扁平结构：扁平文件夹结构可防止深层嵌套问题，并最大限度地降低依赖冲突的风险。

缺点：

• 额外设置： Yarn 需要与 Node.js 分开安装，这为新用户增加了额外的步骤。
• 小型项目的开销：对于小型项目，yarn 的性能提升可能不那么明显，这使得 npm 成为更简单的选择。

2. 锁定文件和确定性构建

npm：package-lock.json

npm 使用 package-lock.json 文件来锁定依赖版本，确保跨环境的安装一致：

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

优点：

• 自动生成： package-lock.json 文件自动生成，有助于确保在所有环境中安装相同版本的依赖项。
• 向后兼容性： 确保较旧的 npm 版本仍然可以正常运行，保持兼容性。

缺点：

• 使用不一致（旧版本）：在旧版本的 npm 中，默认情况下并不总是使用 package-lock.json 文件，这可能会导致安装不一致。

纱线：纱线.lock

Yarn 的yarn.lock 具有相同的用途，但始终默认生成并使用，以确保更具确定性的构建：

# 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...

优点：

• 默认确定性： Yarn 的yarn.lock 文件保证在所有环境中安装一致。
• 始终使用： 与 npm 不同，yarn.lock 文件始终被使用，确保每次安装都是相同的。

缺点：

• 简单项目的开销： 锁定文件的严格性可能感觉像是较小或不太复杂的项目的开销。

3. 安全特性

新项目管理

npm 提供了内置的 npm 审核命令，可通过扫描 npm 安全咨询数据库来检查项目依赖项中的漏洞：

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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