npm：何时使用 `--force` 和 `--legacy-peer-deps`

Question

我是 npm 新手，正在尝试了解重新创建 node_modules 目录以进行部署的工作原理。

我们使用npm ci 而不是npm install 来确保部署过程中的干净状态。但是，当我们在没有任何标志的情况下运行它时，会出现以下错误：

修复上游依赖冲突，或使用--force 或--legacy-peer-deps 重试此命令以接受不正确（且可能损坏）的依赖解析。

npm install 的 documentation 如下（npm ci 的 @ 上没有标志987654322@）：

-f 或 --force 参数将强制 npm 获取远程资源，即使磁盘上存在本地副本。

同时，--legacy-peer-deps 的文档说：

--legacy-peer-deps：安装时忽略所有peerDependencies，采用npm 4到6的风格。

似乎这两个标志都会让npm ci 生成node_modules 目录没有任何问题，但我仍然不清楚两者之间的区别。

据我了解，--force 听起来像是基于最后下载的依赖项，并将覆盖任何以前下载的依赖项。同时，--legacy-peer-deps 听起来它在安装过程中总是会跳过对等依赖项（无论是什么），即使没有问题。

这两个标志有什么区别，我们应该什么时候使用它们？

Answer 1

当项目出现 NPM 版本冲突和错误提示时。

错误

An unhandled exception occurred: The 'buildOptimizer' option cannot be used without 'aot'.

在 .npmrc 文件中

legacy-peer-deps true

命令提示符

npm install 

Answer 2

在新版本的 npm (v7) 中，默认情况下，npm install 在遇到冲突 peerDependencies 时会失败。以前不是这样的。

查看here 了解有关 npm v7 中对等依赖项的更多信息。

两者的区别如下-

• --legacy-peer-deps：安装时忽略所有peerDependencies，采用npm 4到6的风格。

• --strict-peer-deps：遇到任何冲突的peerDependencies 时失败并中止安装过程。默认情况下，npm 只会在根项目的直接依赖引起的 peerDependencies 冲突时崩溃。

Answer 3

在https://github.blog/2021-02-02-npm-7-is-now-generally-available/的文章中

您可以选择使用--force 重试以绕过冲突或 --legacy-peer-deps 命令完全忽略对等依赖项 （此行为类似于版本 4-6）。

我同意这句话不是很清楚，但是“完全忽略对等依赖项”听起来不太好。让我们用一个真实的例子：

这是我npm install时遇到的peer依赖错误：

npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR!
npm ERR! While resolving: mobile@undefined
npm ERR! Found: react@17.0.1
npm ERR! node_modules/react
npm ERR!   react@"17.0.1" from the root project
npm ERR!   peer react@">=16.0.0" from @testing-library/react-native@7.2.0
npm ERR!   node_modules/@testing-library/react-native
npm ERR!     dev @testing-library/react-native@"7.2.0" from the root project
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peer react@"16.13.1" from react-native@0.63.2
npm ERR! node_modules/react-native
npm ERR!   react-native@"https://github.com/expo/react-native/archive/sdk-39.0.4.tar.gz" from the root project
npm ERR!   peer react-native@">=0.59" from @testing-library/react-native@7.2.0
npm ERR!   node_modules/@testing-library/react-native
npm ERR!     dev @testing-library/react-native@"7.2.0" from the root project
npm ERR!
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR!
npm ERR! See /Users/me/.npm/eresolve-report.txt for a full report.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/me/.npm/_logs/2021-03-13T00_10_33_813Z-debug.log
npm ERR! code 1
npm ERR! path /Users/me/my-app
npm ERR! command failed
npm ERR! command sh -c sh ./bin/setup.sh

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/me/.npm/_logs/2021-03-13T00_10_33_860Z-debug.log

下面是--legacy-peer-deps和--force之间的package-lock.json区别。

1. 如果我运行 npm install --legacy-peer-deps，它会将其添加到我的 package-lock.json：

"node_modules/@unimodules/react-native-adapter": {
  "version": "5.7.0",
  "resolved": "https://registry.npmjs.org/@unimodules/react-native-adapter/-/react-native-adapter-5.7.0.tgz",
  "integrity": "sha512-L557/+sc8ZKJVgo1734HF1QNCxrt/fpqdmdNgySJT+kErux/AJNfPq3flsK0fyJduVmniTutYIMyW48cFoPKDA==",
  "dependencies": {
    "invariant": "^2.2.4",
    "lodash": "^4.5.0"
  },
  "peerDependencies": {
    "react-native": "*",
    "react-native-web": "~0.13.7"
  }
},

...

"@unimodules/react-native-adapter": {
  "version": "5.7.0",
  "resolved": "https://registry.npmjs.org/@unimodules/react-native-adapter/-/react-native-adapter-5.7.0.tgz",
  "integrity": "sha512-L557/+sc8ZKJVgo1734HF1QNCxrt/fpqdmdNgySJT+kErux/AJNfPq3flsK0fyJduVmniTutYIMyW48cFoPKDA==",
  "requires": {
    "invariant": "^2.2.4",
    "lodash": "^4.5.0"
  }
},

1. 如果我改用npm install --force，它会添加

"node_modules/expo/node_modules/@unimodules/react-native-adapter": {
  "version": "5.7.0",
  "resolved": "https://registry.npmjs.org/@unimodules/react-native-adapter/-/react-native-adapter-5.7.0.tgz",
  "integrity": "sha512-L557/+sc8ZKJVgo1734HF1QNCxrt/fpqdmdNgySJT+kErux/AJNfPq3flsK0fyJduVmniTutYIMyW48cFoPKDA==",
  "dependencies": {
    "invariant": "^2.2.4",
    "lodash": "^4.5.0"
  },
  "peerDependencies": {
    "react-native": "*",
    "react-native-web": "~0.13.7"
  }
},
"node_modules/expo/node_modules/inline-style-prefixer": {
  "version": "5.1.2",
  "resolved": "https://registry.npmjs.org/inline-style-prefixer/-/inline-style-prefixer-5.1.2.tgz",
  "integrity": "sha512-PYUF+94gDfhy+LsQxM0g3d6Hge4l1pAqOSOiZuHWzMvQEGsbRQ/ck2WioLqrY2ZkHyPgVUXxn+hrkF7D6QUGbA==",
  "peer": true,
  "dependencies": {
    "css-in-js-utils": "^2.0.0"
  }
},
"node_modules/expo/node_modules/react-native-web": {
  "version": "0.13.18",
  "resolved": "https://registry.npmjs.org/react-native-web/-/react-native-web-0.13.18.tgz",
  "integrity": "sha512-WR/0ECAmwLQ2+2cL2Ur+0/swXFAtcSM0URoADJmG6D4MnY+wGc91JO8LoOTlgY0USBOY+qG/beRrjFa+RAuOiA==",
  "peer": true,
  "dependencies": {
    "array-find-index": "^1.0.2",
    "create-react-class": "^15.6.2",
    "deep-assign": "^3.0.0",
    "fbjs": "^1.0.0",
    "hyphenate-style-name": "^1.0.3",
    "inline-style-prefixer": "^5.1.0",
    "normalize-css-color": "^1.0.2",
    "prop-types": "^15.6.0",
    "react-timer-mixin": "^0.13.4"
  },
  "peerDependencies": {
    "react": ">=16.5.1",
    "react-dom": ">=16.5.1"
  }
},

...

  "dependencies": {
    "@unimodules/react-native-adapter": {
      "version": "5.7.0",
      "resolved": "https://registry.npmjs.org/@unimodules/react-native-adapter/-/react-native-adapter-5.7.0.tgz",
      "integrity": "sha512-L557/+sc8ZKJVgo1734HF1QNCxrt/fpqdmdNgySJT+kErux/AJNfPq3flsK0fyJduVmniTutYIMyW48cFoPKDA==",
      "requires": {
        "invariant": "^2.2.4",
        "lodash": "^4.5.0"
      }
    },
    "inline-style-prefixer": {
      "version": "5.1.2",
      "resolved": "https://registry.npmjs.org/inline-style-prefixer/-/inline-style-prefixer-5.1.2.tgz",
      "integrity": "sha512-PYUF+94gDfhy+LsQxM0g3d6Hge4l1pAqOSOiZuHWzMvQEGsbRQ/ck2WioLqrY2ZkHyPgVUXxn+hrkF7D6QUGbA==",
      "peer": true,
      "requires": {
        "css-in-js-utils": "^2.0.0"
      }
    },
    "react-native-web": {
      "version": "0.13.18",
      "resolved": "https://registry.npmjs.org/react-native-web/-/react-native-web-0.13.18.tgz",
      "integrity": "sha512-WR/0ECAmwLQ2+2cL2Ur+0/swXFAtcSM0URoADJmG6D4MnY+wGc91JO8LoOTlgY0USBOY+qG/beRrjFa+RAuOiA==",
      "peer": true,
      "requires": {
        "array-find-index": "^1.0.2",
        "create-react-class": "^15.6.2",
        "deep-assign": "^3.0.0",
        "fbjs": "^1.0.0",
        "hyphenate-style-name": "^1.0.3",
        "inline-style-prefixer": "^5.1.0",
        "normalize-css-color": "^1.0.2",
        "prop-types": "^15.6.0",
        "react-timer-mixin": "^0.13.4"
      }
    }
  }
},

如您所见，npm install --force 仍然固定了许多更严格的依赖版本。

因此，对于 npm 7，如果 npm install 由于对等依赖问题而失败，您可能会首先尝试 npm install --force。