之前咱们曾经实现了一个不带依赖预构建版本的vite, 在vite2.0中减少了一个代表性优化策略 依赖预构建
明天咱们也来手写一个。
咱们要实现的性能如下图所示:
- 依赖预构建性能
- 实现对SFC的解析
- 实现对vue3语法的解析
- 实现对html和js的解析
- 最初实现一个对数字的加减操作性能
代码分两局部
- 依赖预构建局部
- 本地服务局部
先开始编写依赖预构建局部
先把所须要的依赖引入
const http = require('http');const path = require('path');const url = require('url');const querystring = require('querystring');const glob = require('fast-glob'); // 在规定范畴内查问指定的文件，并返回绝对路径const { build } = require('esbuild'); // 打包编译esm模块const fs = require('fs');const os = require('os'); // 获取以后的零碎信息const { createHash } = require('crypto'); // 加密应用const { init, parse } = require('es-module-lexer'); // 查问出代码中应用import局部信息const MagicString = require('magic-string');// 替换代码中门路const compilerSfc = require('@vue/compiler-sfc');// 将sfc转化为json数据const compilerDom = require('@vue/compiler-dom');// 将template转化为render函数编写依赖预构建主函数
async function optimizeDeps() { // 第一步:设置缓存存储的地位 let cacheDir = 'node_modules/.vite'; const dataPath = path.join(cacheDir, '_metadata.json'); const mainHash = getDepHash(); const data = { hash: mainHash, browserHash: mainHash, optimized: {}, }; if (fs.existsSync(dataPath)) { let prevData; try { // 解析.vite下的_metadata.json文件 prevData = JSON.parse(fs.readFileSync(dataPath, 'utf-8')); } catch (error) { console.log(error); } // 哈希是统一的，不须要从新绑定 if (prevData && prevData.hash === data.hash) { return prevData; } } if (fs.existsSync(cacheDir)) { // 如果node_modules/.vite这个文件存在则清空.vite下的所有文件 emptyDir(cacheDir); } else { fs.mkdirSync(cacheDir, { recursive: true }); } // 第二步:收集依赖模块门路 const { deps, missing } = await scanImports(); // { // 'vue': ''C:\\Users\\dftd\\desktop\\vite\\node-vue\\node_modules\\vue\\dist\\vue.runtime.esm-bundler.js'' // } console.log('deps', deps); // update browser hash data.browserHash = createHash('sha256') .update(data.hash + JSON.stringify(deps)) .digest('hex') .substr(0, 8); const qualifiedIds = Object.keys(deps); // 如果没有找到任何依赖，那么间接把data数据写入.vite/_metadata.json if (!qualifiedIds.length) { fs.writeFileSync(dataPath, data); return data; } // 第三步: 对收集的依赖进行解决 // 比方deps的数据是 { 'plamat/byte': 'C:\\Users\\dftd\\node_modules\\vue\\dist\\byte.js' } const flatIdDeps = {}; // 这个对象存储的是 { plamat_byte: 'path' } 的模式 const idToExports = {}; // 这个对象存储的是{ plamat/byte: 'souce'} 的模式 const flatIdToExports = {}; // 这个对象存储的是{ plamat/byte: 'souce'} 的模式 await init; // 将 例如 node/example ==> node_example const flattenId = (id) => id.replace(/[\/\.]/g, '_'); for (const id in deps) { const flatId = flattenId(id); flatIdDeps[flatId] = deps[id]; const entryContent = fs.readFileSync(deps[id], 'utf-8'); const exportsData = parse(entryContent); for (const { ss, se } of exportsData[0]) { const exp = entryContent.slice(ss, se); if (/export\s+\*\s+from/.test(exp)) { exportsData.hasReExports = true; } } idToExports[id] = exportsData; flatIdToExports[flatId] = exportsData; } const define = { 'process.env.NODE_ENV': 'development', }; console.log('flatIdDeps', flatIdDeps); function esbuildVitePlugin(flatIdDeps) { return { name: 'vite-scan', setup(build) { build.onResolve({ filter: /\*/ }, (args) => { console.log('打印后果', args); }); }, }; } const result = await build({ absWorkingDir: process.cwd(), // entryPoints: Object.keys(flatIdDeps), entryPoints: Object.values(flatIdDeps), bundle: true, format: 'esm', outdir: cacheDir, // 配置打完包的文件存储的地位 cacheDir默认为 treeShaking: true, metafile: true, define, // plugins: [esbuildVitePlugin(flatIdDeps)], }); // console.log('result', result); const metafile = result.metafile; // 将 _metadata.json 写入 .vite const cacheDirOutputPath = path.relative(process.cwd(), cacheDir); // console.log(cacheDirOutputPath); for (const id in deps) { // p ==> C:\Users\dftd\desktop\vite\node-vue\node_modules\.vite\vue.js // normalizePath(p) ==> C:/Users/dftd/desktop/vite/node-vue/node_modules/.vite/vue.js const p = path.resolve(cacheDir, flattenId(id) + '.js'); const entry = deps[id]; data.optimized[id] = { file: normalizePath(p), src: normalizePath(entry), needsInterop: false, }; } fs.writeFileSync(dataPath, JSON.stringify(data, null, 2)); return data;}function normalizePath(id) { const isWindows = os.platform() === 'win32'; return path.posix.normalize(isWindows ? id.replace(/\\/g, '/') : id);}// 将此我的项目的xxx.lock.json文件和局部vite配置内容生成一个hashfunction getDepHash() { // 读取xxx.lock.json文件的内容 const content = lookupFile() || ''; const cryptographicStr = createHash('sha256') .update(content) .digest('hex') .substring(0, 8); return cryptographicStr;}// 读取xxx.lock.json文件的内容function lookupFile() { const lockfileFormats = ['package-lock.json', 'yarn.lock', 'pnpm-lock.yaml']; let content = null; for (let index = 0; index < lockfileFormats.length; index++) { const lockPath = path.resolve(__dirname, lockfileFormats[index]); const isExist = fs.existsSync(lockPath, 'utf-8'); if (isExist) { content = fs.readFileSync(lockPath); break; } } // for (const index of lockfileFormats) { // console.log(index); // const lockPath = path.resolve(__dirname, index); // const isExist = fs.existsSync(lockPath, 'utf-8'); // if (isExist) { // content = fs.readFileSync(lockPath); // return content; // } // } return content;}function emptyDir(dir) { for (const file of fs.readdirSync(dir)) { const abs = path.resolve(dir, file); if (fs.lstatSync(abs).isDirectory()) { emptyDir(abs); fs.rmdirSync(abs); } else { fs.unlinkSync(abs); } }}// esbuild pluginfunction esbuildScanPlugin(deps) { return { name: 'dep-scan', setup(build) { // 解析index.html build.onResolve({ filter: /\.(html|vue)$/ }, (args) => { // console.log(args); // const path1 = path.resolve(__dirname, args.path); return { path: args.path, namespace: 'html', }; }); // 加载以后index.html 文件 返回出 main.js build.onLoad( { filter: /\.(html|vue)$/, namespace: 'html' }, async ({ path: ids }) => { const scriptModuleRE = /(<script\b[^>]*type\s*=\s*(?:"module"|'module')[^>]*>)(.*?)<\/script>/gims; const srcRE = /\bsrc\s*=\s*(?:"([^"]+)"|'([^']+)'|([^\s'">]+))/im; const langRE = /\blang\s*=\s*(?:"([^"]+)"|'([^']+)'|([^\s'">]+))/im; const scriptRE = /(<script\b(?:\s[^>]*>|>))(.*?)<\/script>/gims; const importsRE = /(?:^|;|\*\/)\s*import(?!\s+type)(?:[\w*{}\n\r\t, ]+from\s*)?\s*("[^"]+"|'[^']+')\s*(?:$|;|\/\/|\/\*)/gm; let raw = fs.readFileSync(ids, 'utf-8'); raw = raw.replace(/<!--(.|[\r\n])*?-->/, '<!---->'); const isHtml = ids.endsWith('.html'); const regex = isHtml ? scriptModuleRE : scriptRE; regex.lastIndex = 0; let js = ''; let loader = 'js'; let match; while ((match = regex.exec(raw))) { const [, openTag, content] = match; const srcMatch = openTag.match(srcRE); const langMatch = openTag.match(langRE); const lang = langMatch && (langMatch[1] || langMatch[2] || langMatch[3]); if (lang === 'ts' || lang === 'tsx' || lang === 'jsx') { loader = lang; } if (srcMatch) { const src = srcMatch[1] || srcMatch[2] || srcMatch[3]; js += `import ${JSON.stringify(src)}\n`; } else if (content.trim()) { js += content + '\n'; } } if ( loader.startsWith('ts') && (ids.endsWith('.svelte') || (ids.endsWith('.vue') && /<script\s+setup/.test(raw))) ) { // when using TS + (Vue + <script setup>) or Svelte, imports may seem // unused to esbuild and dropped in the build output, which prevents // esbuild from crawling further. // the solution is to add `import 'x'` for every source to force // esbuild to keep crawling due to potential side effects. let m; const original = js; while ((m = importsRE.exec(original)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === importsRE.lastIndex) { importsRE.lastIndex++; } js += `\nimport ${m[1]}`; } } if (!js.includes(`export default`)) { js += `\nexport default {}`; } return { loader, contents: js, }; }, ); // 解析第三方库的esm js模块文件 间接走打包 build.onResolve( { // avoid matching windows volume filter: /\.js\?v=1$/, }, ({ path: id, importer }) => { return { path: id, external: true, }; }, ); // 解析.js 文件 build.onResolve( { // avoid matching windows volume filter: /main\.js$/, }, ({ path: id, importer }) => { return { path: id, namespace: 'mianJs', }; }, ); // 加载.js文件的内容 build.onLoad( { filter: /main\.js$/, namespace: 'mianJs' }, ({ path: id }) => { const c = fs.readFileSync(id, 'utf-8'); const magicString = new MagicString(c); let imports = parse(c)[0]; imports.forEach((i) => { const { s, e, n } = i; let absolutePath = path.resolve(__dirname, 'node_modules', n); const isExist = fs.existsSync(absolutePath); if (isExist) { const modulePath = require(absolutePath + '/package.json').module; const esmPath = path.resolve(absolutePath, modulePath); magicString.overwrite(s, e, `${esmPath}?v=1`); deps[n] = esmPath; } else { // let aa = path.resolve(__dirname, n); // magicString.overwrite(s, e, aa); } }); return { loader: 'js', contents: magicString.toString(), }; }, ); }, };}// 收集依赖模块门路 返回一个依赖合集对象async function scanImports() { const deps = {}; const missing = {}; let entries; // 查问出当前目录下后缀为html的文件 entries = await glob('**/*.html', { cwd: process.cwd(), ignore: ['**/node_modules/**'], absolute: true, }); // entries => [ 'C:/Users/dftd/Desktop/vite/node-vue/index.html' ] // console.log('entries', entries); if (!entries.length) { return { deps: {}, missing: {}, }; } const scanPath = esbuildScanPlugin(deps); // 应用 esbuild 进行一次打包，打包过程中就找到了deps和missing,最初返回deps和missing // Promise.all( // entries.map((entry) => { // console.log(222); // await build({ // absWorkingDir: process.cwd(), // 工作的目录 // entryPoints: [entry], // 入口文件(个别为index.html) // write: false, // build API能够间接写入文件系统 默认状况下，JavaScript API会写入文件系统 // bundle: true, // 应用analyze性能生成一个对于bundle内容的易于浏览的报告 // format: 'esm', // 输入的类型 （iife, cjs, esm） // plugins: [scanPath], // }); // }), // ); await build({ absWorkingDir: process.cwd(), // 工作的目录 entryPoints: entries, // 入口文件(个别为index.html) write: false, // build API能够间接写入文件系统 默认状况下，JavaScript API会写入文件系统 bundle: true, // 应用analyze性能生成一个对于bundle内容的易于浏览的报告 format: 'esm', // 输入的类型 （iife, cjs, esm） plugins: [scanPath], }); return { deps, missing, };}依赖预构建总结:
依赖预构建产生在在本地服务启动之前执行, 大抵过程分为两步，第一步就是依赖的收集（这部分用到了esbuild build办法来收集所有的依赖门路），第二部是把这些收集的依赖门路再次用esbuild build办法进行编译，编译的后果存储到node_modules/.vite中, 并且还创立了一份_metadata.json文件对构建出的依赖做记录。
接下来编写本地服务局部
function createServer() { optimizeDeps(); const serve = {}; let httpServe = http.createServer((req, res) => { let pathName = url.parse(req.url).pathname; // console.log(22, pathName); if (pathName == '/') { pathName = '/index.html'; } let extName = path.extname(pathName); let extType = ''; switch (extName) { case '.html': extType = 'text/html'; break; case '.js': extType = 'application/javascript'; break; case '.css': extType = 'text/css'; break; case '.ico': extType = 'image/x-icon'; break; case '.vue': extType = 'application/javascript'; break; default: extType = 'text/html'; } if (/.vite/.test(pathName)) { // 间接加载预构建好的包 resolveViteModules(pathName, extType, res); } else if (/\/@modules\//.test(pathName)) { // 加载那些没有预构建好的包第三方包 resolveNodeModules(pathName, res); } else { // 加载非第三方包文件 resolveModules(pathName, extName, extType, res, req); } }); serve.listen = () => { httpServe.listen(7777); }; return serve;}// 重写门路function rewriteImports(source) { let imports = parse(source)[0]; const magicString = new MagicString(source); if (imports.length) { for (let index = 0; index < imports.length; index++) { const { s, e } = imports[index]; // 失去以后引入的第三方库的name const id = source.substring(s, e); if (/^[^\.\/]/.test(id)) { // 依据id到node_modules/.vite/_metadata.json中查问以后这个包是否存在 const _metadataPath = path.resolve( __dirname, 'node_modules/.vite/_metadata.json', ); const _metaContent = require(_metadataPath).optimized; console.log('_metaContent', _metaContent); if (_metaContent[id]) { magicString.overwrite(s, e, `/node_modules/.vite/${id}`); } else { magicString.overwrite(s, e, `/@modules/${id}`); } } } } return magicString.toString();}// 解决加载非第三方包文件function resolveModules(pathName, extName, extType, res, req) { fs.readFile(`.${pathName}`, 'utf-8', (err, data) => { if (err) { throw err; } console.log('extName', extName); console.log('extType', extType); res.writeHead(200, { 'Content-Type': `${extType}; charset=utf-8`, }); if (extName == '.vue') { const query = querystring.parse(url.parse(req.url).query); const ret = compilerSfc.parse(data); const { descriptor } = ret; if (!query.type) { // 解析出vue文件script局部 const scriptBlock = descriptor.script.content; const newScriptBlock = rewriteImports( scriptBlock.replace('export default', 'const __script = '), ); const newRet = ` ${newScriptBlock} import { render as __render } from '.${pathName}?type=template' __script.render = __render export default __script `; res.write(newRet); } else { // 解析出vue文件template局部 生成render函数 const templateBlock = descriptor.template.content; const compilerTemplateBlockRender = rewriteImports( compilerDom.compile(templateBlock, { mode: 'module', }).code, ); res.write(compilerTemplateBlockRender); } } else if (extName == '.js') { const r = rewriteImports(data); res.write(r); } else { res.write(data); } res.end(); });}// 在node_modules 中读取没有预构建好的资源function resolveNodeModules(pathName, res) { const id = pathName.replace(/\/@modules\//, ''); // 如果是加载的是第三方包 // 获取第三方包的相对地址 let absolutePath = path.resolve(__dirname, 'node_modules', id); // console.log('absolutePath', absolutePath); // 获取第三方包的esm的包地址 const modulePath = require(absolutePath + '/package.json').module; const esmPath = path.resolve(absolutePath, modulePath); // console.log('esmPath', esmPath); // const pkgPath = `./node_modules/${id}/${modulePath}`; fs.readFile(esmPath, 'utf-8', (err, data) => { if (err) { throw err; } res.writeHead(200, { 'Content-Type': `application/javascript; charset=utf-8`, }); // const b = cjsEs6(data); // console.log(b); const r = rewriteImports(data); // console.log(r); res.write(r); res.end(); });}// 加载.vite预构建好的包function resolveViteModules(pathName, extType, res) { const id = pathName.replace(/\/node_modules\/.vite\//, ''); // 依据id到node_modules/.vite/_metadata.json中查问以后这个包是否存在 const _metadataPath = path.resolve( __dirname, 'node_modules/.vite/_metadata.json', ); const _metaContent = require(_metadataPath).optimized; const { src, file } = _metaContent[id]; // 提取以后文件门路中的文件名称 const absFileName = path.basename(src); const absFile = path.resolve(__dirname, 'node_modules/.vite', absFileName); const content = fs.readFileSync(absFile, 'utf-8'); // console.log(1111, content); // console.log(222, absFile); res.writeHead(200, { 'Content-Type': `application/javascript; charset=utf-8`, }); res.write(content); res.end();}const serve = createServer();serve.listen();本地服务局部总结:
我在上一篇中写过一篇不带预构建版本的vite，这个版本是在之前的根底重写了rewriteImports办法把门路重写改为/node_modules/.vite 能够间接加载预构建好的文件, 如果你还没有看我的不带预构建版本的vite倡议先看下，由浅入深能力更好的了解vite的实质原理。