Serving Static Files
1. Using express.static() Middleware
Form Effect express.static("public")Serve at root app.use("/static", express.static("public"))Mount under prefix express.static("public", opts)Pass serve-static options
2. Setting Static Directory
Example: Absolute path
import path from "node:path" ; import { fileURLToPath } from "node:url" ; const __dirname = path. dirname ( fileURLToPath ( import . meta .url)); app. use (express. static (path. join (__dirname, "public" )));
Warning: Always use absolute paths — relative paths resolve from the CWD where Node was launched, breaking PM2 / systemd setups.
3. Serving Multiple Static Directories
Example: Order matters (first found wins)
app. use (express. static ( "dist" )); // Built assets app. use (express. static ( "public" )); // Untouched static
4. Setting Virtual Path Prefix
Example: Mount under /assets
app. use ( "/assets" , express. static ( "public" )); // File public/logo.png → GET /assets/logo.png
Benefit Detail Decoupling URL doesn't expose folder name Versioning /assets/v2/...CDN aliasing Match CDN path
Asset Type maxAge immutable Hashed bundles (app.[hash].js) 1ytrue Images 30dfalse index.html0false (no-cache)
Example: Long-cache hashed assets
app. use ( "/static" , express. static ( "dist" , { maxAge: "1y" , immutable: true , setHeaders : ( res , filePath ) => { if (filePath. endsWith ( ".html" )) res. setHeader ( "Cache-Control" , "no-cache" ); } }));
6. Setting Index Files
Setting Effect index: "index.html"Default index: ["index.html", "index.htm"]Try in order index: falseDisable index serving
7. Enabling Directory Listing
Example: serve-index for browsing
import serveIndex from "serve-index" ; app. use ( "/files" , express. static ( "uploads" ), serveIndex ( "uploads" , { icons: true }));
Warning: Never enable directory listing in production for sensitive folders — exposes filenames.
Option Default Purpose etagtrueGenerate weak ETag from inode/size/mtime lastModifiedtrueSend Last-Modified header
Client request 1: GET /logo.png
Server response: 200 OK + ETag: "abc123"
Client request 2: GET /logo.png + If-None-Match: "abc123"
Server response: 304 Not Modified ← no body, saves bandwidth
9. Handling Fallback Files
Example: SPA fallback to index.html
app. use (express. static ( "dist" )); // Catch-all: serve SPA for unknown paths (Express 5) app. get ( "/{*splat}" , ( req , res ) => { res. sendFile (path. join (__dirname, "dist/index.html" )); });
Use Case Pattern SPA Catch-all → index.html Multi-tenant Per-tenant static dir
10. Serving Hidden Files
dotfiles Behavior "ignore" (default)404 + skip dotfiles "deny"403 Forbidden "allow"Serve normally
Example: Allow .well-known for ACME
app. use (express. static ( "public" , { dotfiles: "allow" })); // Or scope it to ACME challenge only app. use ( "/.well-known" , express. static ( ".well-known" , { dotfiles: "allow" }));