从 vue3 和 vite 源码中，我学到了一行代码统一规范团队包管理器的神器

1. 如何学习调试源码2. 学会 npm 钩子3. 学会 "preinstall": "npx only-allow pnpm" 一行代码统一规范包管理器4. 学到 only-allow 原理5. 等等

// vue-next/package.json{  "private": true,  "version": "3.2.22",  "scripts": {    "preinstall": "node ./scripts/preinstall.js",  }}

依次执行# install 之前执行这个脚本preinstall# 执行 install 脚本install# install 之后执行这个脚本postinstall

// vue-next/scripts/preinstall.js
if (!/pnpm/.test(process.env.npm_execpath || '')) {  console.warn(    `\u001b[33mThis repository requires using pnpm as the package manager ` +      ` for scripts to work properly.\u001b[39m\n`  )  process.exit(1)}

{  "scripts": {    "preinstall": "npx only-allow pnpm -y"  }}

# 推荐克隆我的源码库git clone https://github.com/lxchuan12/only-allow-analysis.gitcd only-allow-analysis/only-allow# npm i -g pnpmpnpm i
# 或者克隆官方仓库git clone https://github.com/pnpm/only-allow.gitcd only-allow# npm i -g pnpmpnpm i

{  "scripts": {    "preinstall": "npx only-allow yarn"  }}

// only-allow/package.json{  "bin": "bin.js",}

// only-allow/package.json{  "scripts": {    "preinstall": "node bin.js pnpm"  },}

// only-allow/bin.js#!/usr/bin/env nodeconst whichPMRuns = require('which-pm-runs')// 输出边框盒子const boxen = require('boxen')
const argv = process.argv.slice(2)if (argv.length === 0) {  console.log('Please specify the wanted package manager: only-allow <npm|pnpm|yarn>')  process.exit(1)}// 第一个参数则是 用户传入的希望使用的包管理器// 比如 npx only-allow pnpm // 这里调试是 node bin.js pnpmconst wantedPM = argv[0]// npm pnpm yarn 都不是，则报错if (wantedPM !== 'npm' && wantedPM !== 'pnpm' && wantedPM !== 'yarn') {  console.log(`"${wantedPM}" is not a valid package manager. Available package managers are: npm, pnpm, or yarn.`)  process.exit(1)}// 使用的包管理器const usedPM = whichPMRuns()// 希望使用的包管理器 不相等，则报错。// - npm  提示使用 npm install// - pnpm 提示使用 pnpm install// - yarn 提示使用 yarn install// 最后退出进程if (usedPM && usedPM.name !== wantedPM) {  const boxenOpts = { borderColor: 'red', borderStyle: 'double', padding: 1 }  switch (wantedPM) {    case 'npm':      console.log(boxen('Use "npm install" for installation in this project', boxenOpts))      break    case 'pnpm':      console.log(boxen(`Use "pnpm install" for installation in this project.
If you don't have pnpm, install it via "npm i -g pnpm".For more details, go to https://pnpm.js.org/`, boxenOpts))      break    case 'yarn':      console.log(boxen(`Use "yarn" for installation in this project.
If you don't have Yarn, install it via "npm i -g yarn".For more details, go to https://yarnpkg.com/`, boxenOpts))      break  }  process.exit(1)}

'use strict'
module.exports = function () {  if (!process.env.npm_config_user_agent) {    return undefined  }  return pmFromUserAgent(process.env.npm_config_user_agent)}
function pmFromUserAgent (userAgent) {  const pmSpec = userAgent.split(' ')[0]  const separatorPos = pmSpec.lastIndexOf('/')  return {    name: pmSpec.substr(0, separatorPos),    version: pmSpec.substr(separatorPos + 1)  }}