Express.js Cheatsheet - Express Middleware & API Reference
All essential Express.js commands organized by use case, with 45+ entries you can copy and run directly. Find the right command fast when you need it.
Back to LanguagesApp Creation 5
const app = express()Create应用实例
app.use(express.json())挂载全局middleware（解析 JSON request体）
app.listen(3000, () => {})监听PortStartService
const router = express.Router()Create可挂载route器
app.set("port", process.env.PORT || 3000)Set应用Configure
Routes 7
app.get("/users", handler)GET route
app.post("/users", handler)POST route
app.put("/users/:id", handler)PUT route，:id 是Options
app.delete("/users/:id", handler)DELETE route
app.all("/api/*", handler)Match所有method的通配route
app.use("/api", router)挂载子routemodule
router.route("/users").get(list).post(create)链式route定义
Request 6
req.params.idURL routeOptions
req.query.page查询stringOptions
req.body.namerequest体（需 express.json()）
req.headers["content-type"]request头
req.cookies.tokenCookie（需 cookie-parser）
req.get("User-Agent")Get指定request头
Response 6
res.send("hello")发送文本response
res.json({ data })返回 JSON
res.status(201).json({ ok: true })Setstate码并返回 JSON
res.redirect("/login")redirect
res.sendFile(path.join(__dirname, "index.html"))发送File
res.set("X-Custom", "value")Setresponse头
Middleware 8
app.use((req, res, next) => { next() })自定义middleware
express.urlencoded({ extended: true })解析 URL 编码表单
app.use("/static", express.static("public"))静态FileService
cors()跨域supportsmiddleware
helmet()安全 HTTP 头middleware
morgan("dev")request日志middleware
cookie-parser()解析 Cookie
compression()responseCompressmiddleware
JWT 6
app.set("view engine", "ejs")Settemplate引擎
app.set("views", path.join(__dirname, "views"))SettemplateDirectory
res.render("index", { title: "Home" })rendertemplate并response
jwt.sign(payload, secret, { expiresIn: "1h" })签发 JWT token
jwt.verify(token, secret)验证 JWT token
req.headers.authorization从request头Get Bearer token
Errors & Patterns 7
const wrap = (fn) => (req, res, next) => fn(req, res, next).catch(next)async错误package装器，自动catch async 错误
app.use((req, res) => res.status(404).send("Not Found"))404 fallback处理
app.use((err, req, res, next) => res.status(500).json({ error: err.message }))全局错误处理middleware（必须 4 个Options）
next(err)传递错误到错误处理middleware
process.on("uncaughtException", handler)catch未处理exception
process.on("unhandledRejection", handler)catch未处理 Promise 拒绝
module.exports = routerExportroutemodule供 app.use 挂载
💡 Tips
- middlewareorder很重要，body-parser 必须在route之前，错误处理middleware必须放最后。
- 错误处理middleware必须 4 个Options (err, req, res, next)，否则 Express 不识别。
- 生产环境用 helmet() 加安全头，cors() 按需Configure白名单。
- express.static 可Set多个Directory，按orderFindFile。
- Router 可module化route，app.use("/api", router) 挂载子route。
Official References
Commands are compiled from the official docs below. Click to verify the latest usage.
Maintained by LaoHand
Publicly updated on Jul 21, 2026, continuously proofread against official docs.
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