前言
前段时间我们有去探索了一下vue-cli、cra的原理，生成项目的过程，他是基于webpack的，但是今天我们的主角是create-vue，他是基于vite的，为什么要使用vite而不是webpack呢？因为vite比webpack快。
我们使用vue-cli和vite快速生成一个项目分别耗时如下：
webpack：
vite：
就目前的图来看vite在构建、启动项目的时候会比webpack快10倍，这还是仅仅只是简单的项目，前端的项目复杂程度本来就是呈指数上升的，这时候vite与webpack可谓是天差地别。那么接下来我将带领大家一步一步去探索vite的各种优点。
准备工作
首先我们接着前言里面如何用vite去初始化一个Vue3的项目吧。
官方推荐使用
npm init vue@latest
这个命令将会去创建一个create-vue脚手架，实际的本质就是去下载create-vue这个包，然后执行index.ts文件。
前置导入模块
import * as fs from 'node:fs'
import * as path from 'node:path'
// fileURLToPath用来获取根路径的，源码里面没有，在下文path.resolve(__dirname, 'template') 那里会报错。
// 原因：因为在package.json里面定义的为ESM规范，而在index.ts文件里面，
出现了Common.js规范，两种规范下的实现是不同的，所以会报错：__dirname is not define
import { fileURLToPath } from 'url'
import minimist from 'minimist' // 解析命令行参数
import prompts from 'prompts' // 命令行交互
import { red, green, bold } from 'kolorist' // 有色输出
// 在控制台打印的banner
// gradientBanner 内容为下面的a变量
// const defaultBanner = 'Vue.js - The Progressive JavaScript Framework'
import * as banners from './utils/banners'
import renderTemplate from './utils/renderTemplate'
import { postOrderDirectoryTraverse, preOrderDirectoryTraverse } from './utils/directoryTraverse'
import generateReadme from './utils/generateReadme'
import getCommand from './utils/getCommand'
import renderEslint from './utils/renderEslint'
工具函数
isValidPackageName
我们发现在cra、vue-cli中都是借助于validate-npm-package-name这个包实现的，这里面选择了重写这个库，省去了库的安装，读取等操作，进而提升速度。
function isValidPackageName(projectName) {
return /^(?:@[a-z0-9-*~][a-z0-9-*._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$/.test(projectName)
}
toValidPackageName
如果包名检查不合法就要把他变为合法的，比如toValidPackageName(myProject) => myproject，还会去空格等。
function toValidPackageName(projectName) {
return projectName
.trim()
.toLowerCase()
.replace(/\s+/g, '-') // 匹配空白字符到的第一个字符开始，直到匹配失败 eg:'lov e' => 'lov-e'
.replace(/^[._]/, '') // 匹配 '.' '_' 为 ''
.replace(/[^a-z0-9-~]+/g, '-') // 包含a-z、 0-9 - ~ 重复多个
}
canSkipEmptying
顾名思义，读取操作文件是否可以跳过
function canSkipEmptying(dir: string) {
if (!fs.existsSync(dir)) { // fs.exists() 如果路径存在，则返回 `true`，否则返回 `false`。
return true
}
const files = fs.readdirSync(dir) // 返回一个不包括 `'.'` 和 `'..'` 的文件名的数组。
if (files.length === 0) {
return true
}
if (files.length === 1 && files[0] === '.git') {
return true
}
return false
}
emptyDir
判断是否是一个空目录
function emptyDir(dir) {
if (!fs.existsSync(dir)) { // fs.exists() 如果路径存在，则返回 `true`，否则返回 `false`。
return
}
postOrderDirectoryTraverse(
dir,
(dir) => fs.rmdirSync(dir), // 同步移除文件夹
(file) => fs.unlinkSync(file) // 同步删除文件，但不删除文件夹
)
}
在index.ts入口文件中，我们发现init作为入口函数，我们来调试一下init函数。
init
async function init() {
console.log()
console.log( // 判断是否在终端上下文中和颜色深度？？？
process.stdout.isTTY && process.stdout.getColorDepth() > 8
? banners.gradientBanner // 彩色的
: banners.defaultBanner // 黑白的
)
console.log()
const cwd = process.cwd() // 获取当前根路径
// possible options:
// --default
// --typescript / --ts
// --jsx
// --router / --vue-router
// --pinia
// --with-tests / --tests (equals to `--vitest --cypress`)
// --vitest
// --cypress
// --playwright
// --eslint
// --eslint-with-prettier (only support prettier through eslint for simplicity)
// --force (for force overwriting)
const argv = minimist(process.argv.slice(2), { // 解析命令行参数 argv位启动目录与当前文件目录
alias: {
typescript: ['ts'],
'with-tests': ['tests'],
router: ['vue-router']
},
string: ['_'],
// all arguments are treated as booleans
boolean: true
})
// if any of the feature flags is set, we would skip the feature prompts
如果设置了这些特性，那么下一次会跳过走预设配置缓存
const isFeatureFlagsUsed =
typeof (
argv.default ??
argv.ts ??
argv.jsx ??
argv.router ??
argv.pinia ??
argv.tests ??
argv.vitest ??
argv.cypress ??
argv.playwright ??
argv.eslint
) === 'boolean'
let targetDir = argv._[0]
const defaultProjectName = !targetDir ? 'vue-project' : targetDir // 默认目录
const forceOverwrite = argv.force // 强制覆盖
可选配置项
// 这时候会在终端弹出可选命令项，这个result就是保存这些选项的。
let result: {
projectName?: string
shouldOverwrite?: boolean
packageName?: string
needsTypeScript?: boolean
needsJsx?: boolean
needsRouter?: boolean
needsPinia?: boolean
needsVitest?: boolean
needsE2eTesting?: false | 'cypress' | 'playwright'
needsEslint?: boolean
needsPrettier?: boolean
} = {}
try {
// Prompts:
// - Project name:
// - whether to overwrite the existing directory or not?
// - enter a valid package name for package.json
// - Project language: JavaScript / TypeScript
// - Add JSX Support?
// - Install Vue Router for SPA development?
// - Install Pinia for state management?
// - Add Cypress for testing?
// - Add Playwright for end-to-end testing?
// - Add ESLint for code quality?
// - Add Prettier for code formatting?
result = await prompts(
[
{
name: 'projectName',
type: targetDir ? null : 'text',
message: 'Project name:',
initial: defaultProjectName,
onState: (state) => (targetDir = String(state.value).trim() || defaultProjectName)
},
{
name: 'shouldOverwrite',
type: () => (canSkipEmptying(targetDir) || forceOverwrite ? null : 'confirm'),
message: () => {
const dirForPrompt =
targetDir === '.' ? 'Current directory' : `Target directory "${targetDir}"`
return `${dirForPrompt} is not empty. Remove existing files and continue?`
}
},
{
name: 'overwriteChecker',
type: (prev, values) => {
if (values.shouldOverwrite === false) {
throw new Error(red('✖') + ' Operation cancelled')
}
return null
}
},
{
name: 'packageName',
type: () => (isValidPackageName(targetDir) ? null : 'text'),
message: 'Package name:',
initial: () => toValidPackageName(targetDir),
validate: (dir) => isValidPackageName(dir) || 'Invalid package.json name'
},
{
name: 'needsTypeScript',
type: () => (isFeatureFlagsUsed ? null : 'toggle'),
message: 'Add TypeScript?',
initial: false,
active: 'Yes',
inactive: 'No'
},
{
name: 'needsJsx',
type: () => (isFeatureFlagsUsed ? null : 'toggle'),
message: 'Add JSX Support?',
initial: false,
active: 'Yes',
inactive: 'No'
},
{
name: 'needsRouter',
type: () => (isFeatureFlagsUsed ? null : 'toggle'),
message: 'Add Vue Router for Single Page Application development?',
initial: false,
active: 'Yes',
inactive: 'No'
},
{
name: 'needsPinia',
type: () => (isFeatureFlagsUsed ? null : 'toggle'),
message: 'Add Pinia for state management?',
initial: false,
active: 'Yes',
inactive: 'No'
},
{
name: 'needsVitest',
type: () => (isFeatureFlagsUsed ? null : 'toggle'),
message: 'Add Vitest for Unit Testing?',
initial: false,
active: 'Yes',
inactive: 'No'
},
{
name: 'needsE2eTesting',
type: () => (isFeatureFlagsUsed ? null : 'select'),
message: 'Add an End-to-End Testing Solution?',
initial: 0,
choices: (prev, answers) => [
{ title: 'No', value: false },
{
title: 'Cypress',
description: answers.needsVitest
? undefined
: 'also supports unit testing with Cypress Component Testing',
value: 'cypress'
},
{
title: 'Playwright',
value: 'playwright'
}
]
},
{
name: 'needsEslint',
type: () => (isFeatureFlagsUsed ? null : 'toggle'),
message: 'Add ESLint for code quality?',
initial: false,
active: 'Yes',
inactive: 'No'
},
{
name: 'needsPrettier',
type: (prev, values) => {
if (isFeatureFlagsUsed || !values.needsEslint) {
return null
}
return 'toggle'
},
message: 'Add Prettier for code formatting?',
initial: false,
active: 'Yes',
inactive: 'No'
}
],
{
onCancel: () => {
throw new Error(red('✖') + ' Operation cancelled')
}
}
)
} catch (cancelled) {
console.log(cancelled.message)
process.exit(1)
}
合并默认配置与选择性配置
// `initial` won't take effect if the prompt type is null
// so we still have to assign the default values here
const {
projectName,
packageName = projectName ?? defaultProjectName,
shouldOverwrite = argv.force,
needsJsx = argv.jsx,
needsTypeScript = argv.typescript,
needsRouter = argv.router,
needsPinia = argv.pinia,
needsVitest = argv.vitest || argv.tests,
needsEslint = argv.eslint || argv['eslint-with-prettier'],
needsPrettier = argv['eslint-with-prettier']
} = result
const { needsE2eTesting } = result
const needsCypress = argv.cypress || argv.tests || needsE2eTesting === 'cypress'
const needsCypressCT = needsCypress && !needsVitest
const needsPlaywright = argv.playwright || needsE2eTesting === 'playwright'
const root = path.join(cwd, targetDir) // 获取根目录
if (fs.existsSync(root) && shouldOverwrite) {
emptyDir(root) //如果根目录是空的，并且强制覆盖那就先删除，再新建
} else if (!fs.existsSync(root)) {
fs.mkdirSync(root) // 如果没有文件，则直接创建
}
console.log(`\nScaffolding project in ${root}...`)
// 生成package.json，写入name、version
const pkg = { name: packageName, version: '0.0.0' }
fs.writeFileSync(path.resolve(root, 'package.json'), JSON.stringify(pkg, null, 2))
// todo:
// work around the esbuild issue that `import.meta.url` cannot be correctly transpiled
// when bundling for node and the format is cjs
// const templateRoot = new URL('./template', import.meta.url).pathname
const __filenameNew = fileURLToPath(import.meta.url) // 获取root
const __dirnameNew = path.dirname(__filenameNew)
const templateRoot = path.resolve(__dirnameNew, 'template')
const render = function render(templateName) {
const templateDir = path.resolve(templateRoot, templateName)
// 这个函数，就是按照配置加载包的defaultConfig的，之后merge进，package.json中
renderTemplate(templateDir, root)
}
根据用户配置加载包的config
// Render base template
render('base')
// Add configs.
if (needsJsx) {
render('config/jsx')
}
if (needsRouter) {
render('config/router')
}
if (needsPinia) {
render('config/pinia')
}
if (needsVitest) {
render('config/vitest')
}
if (needsCypress) {
render('config/cypress')
}
if (needsCypressCT) {
render('config/cypress-ct')
}
if (needsPlaywright) {
render('config/playwright')
}
if (needsTypeScript) {
render('config/typescript')
// Render tsconfigs
render('tsconfig/base')
if (needsCypress) {
render('tsconfig/cypress')
}
if (needsCypressCT) {
render('tsconfig/cypress-ct')
}
if (needsPlaywright) {
render('tsconfig/playwright')
}
if (needsVitest) {
render('tsconfig/vitest')
}
}
// Render ESLint config
if (needsEslint) {
renderEslint(root, { needsTypeScript, needsCypress, needsCypressCT, needsPrettier })
}
// Render code template.
// prettier-ignore
const codeTemplate =
(needsTypeScript ? 'typescript-' : '') +
(needsRouter ? 'router' : 'default')
render(`code/${codeTemplate}`)
// Render entry file (main.js/ts).
if (needsPinia && needsRouter) {
render('entry/router-and-pinia')
} else if (needsPinia) {
render('entry/pinia')
} else if (needsRouter) {
render('entry/router')
} else {
render('entry/default')
}
// Cleanup.
// We try to share as many files between TypeScript and JavaScript as possible.
// If that's not possible, we put `.ts` version alongside the `.js` one in the templates.
// So after all the templates are rendered, we need to clean up the redundant files.
// (Currently it's only `cypress/plugin/index.ts`,
but we might add more in the future.)
// (Or, we might completely get rid of the plugins
folder as Cypress 10 supports `cypress.config.ts`)
if (needsTypeScript) {
// Convert the JavaScript template to the TypeScript
// Check all the remaining `.js` files:
// - If the corresponding TypeScript version already exists, remove the `.js` version.
// - Otherwise, rename the `.js` file to `.ts`
// Remove `jsconfig.json`, because we already have tsconfig.json
// `jsconfig.json` is not reused, because we use solution-style
`tsconfig`s, which are much more complicated.
preOrderDirectoryTraverse(
root,
() => {},
(filepath) => {
if (filepath.endsWith('.js')) {
const tsFilePath = filepath.replace(/\.js$/, '.ts')
if (fs.existsSync(tsFilePath)) {
fs.unlinkSync(filepath)
} else {
fs.renameSync(filepath, tsFilePath)
}
} else if (path.basename(filepath) === 'jsconfig.json') {
fs.unlinkSync(filepath)
}
}
)
生成入口index.html文件
// Rename entry in `index.html`
const indexHtmlPath = path.resolve(root, 'index.html')
const indexHtmlContent = fs.readFileSync(indexHtmlPath, 'utf8')
fs.writeFileSync(indexHtmlPath, indexHtmlContent.replace('src/main.js', 'src/main.ts'))
} else {
// Remove all the remaining `.ts` files
preOrderDirectoryTraverse(
root,
() => {},
(filepath) => {
if (filepath.endsWith('.ts')) {
fs.unlinkSync(filepath)
}
}
)
}
包管理器的选择使用
const userAgent = process.env.npm_config_user_agent ?? ''
const packageManager = /pnpm/.test(userAgent) ? 'pnpm' : /yarn/.test(userAgent) ? 'yarn' : 'npm'
生成README.md
fs.writeFileSync(
path.resolve(root, 'README.md'),
generateReadme({
projectName: result.projectName ?? result.packageName ?? defaultProjectName,
packageManager,
needsTypeScript,
needsVitest,
needsCypress,
needsPlaywright,
needsCypressCT,
needsEslint
})
)
终端输出，初始化完成
console.log(`\nDone. Now run:\n`)
if (root !== cwd) {
console.log(` ${bold(green(`cd ${path.relative(cwd, root)}`))}`) // cd myproject
}
console.log(` ${bold(green(getCommand(packageManager, 'install')))}`) // npm|yarn|pnpm install
if (needsPrettier) {
console.log(` ${bold(green(getCommand(packageManager, 'lint')))}`) // eslint检查 npm|yarn|pnpm lint
}
console.log(` ${bold(green(getCommand(packageManager, 'dev')))}`) // 启动 npm|yarn|pnpm dev
console.log()
}
到这里就可以在根目录生成一个项目，我们可以用vite来启动项目啦！
总结
create-vue不仅仅自己写了包名核检函数，还有终端颜色输出的模块，这个脚手架支持jsx、pinia等多种配置，每一种配置又是一个单独的包，整个文件下来就是以前的那一套，可选配置、package.json的生成、配置合并、终端输出等。这里仅仅是初始化一个项目而已，更重要的是用vite来启动服务，构建打包，值得一提的是，在开发环境vite打包是是用的自己的一套(esBuild)，在生产环境vite直接借用了rollup工具进行打包，这个在我的前端构建工具vite进阶系列将会详细介绍。
