# sirv ![CI](https://github.com/lukeed/sirv/workflows/CI/badge.svg) > The optimized and lightweight middleware for serving requests to static assets You may use `sirv` as a *very* fast and lightweight alternative to [`serve-static`](https://www.npmjs.com/package/serve-static). The massive performance advantage over `serve-static` is explained by **not** relying on the file system for existence checks on every request. These are expensive interactions and must be avoided whenever possible! Instead, when not in "dev" mode, `sirv` performs all its file-system operations upfront and then relies on its cache for future operations. This middleware will work out of the box for [Polka](https://github.com/lukeed/polka), Express, and other Express-like frameworks. It will also work with the native `http`, `https` and `http2` modules. It requires _very_ little effort to modify/wrap it for servers that don't accept the `(req, res, next)` signature. :bulb: For a feature-complete CLI application, check out the sibling [`sirv-cli`](https://github.com/lukeed/sirv/tree/master/packages/sirv-cli) package as an alternative to [`zeit/serve`](https://github.com/zeit/serve)~! ## Install ``` $ npm install --save sirv ``` ## Usage ```js const sirv = require('sirv'); const polka = require('polka'); const compress = require('compression')(); // Init `sirv` handler const assets = sirv('public', { maxAge: 31536000, // 1Y immutable: true }); polka() .use(compress, assets) .use('/api', require('./api')) .listen(3000, err => { if (err) throw err; console.log('> Ready on localhost:3000~!'); }); ``` ## API ### sirv(dir, opts={}) Returns: `Function` The returned function is a middleware in the standard Express-like signature: `(req, res, next)`, where `req` is the [`http.IncomingMessage`](https://nodejs.org/api/http.html#http_class_http_incomingmessage), `res` is the [`http.ServerResponse`](https://nodejs.org/dist/latest-v9.x/docs/api/http.html#http_class_http_serverresponse), and `next` (in this case) is the function to call if no file was found for the given path. When defined, a `next()` callback is always called _instead of_ the [`opts.onNoMatch`](#optsonnomatch) callback. However, unlike `onNoMatch`, your `next()` is given no arguments. #### dir Type: `String`
Default: `.` The directory from which to read and serve assets. It is resolved to an absolute path — you must provide an absolute path yourself if `process.cwd()` is not the correct assumption. #### opts.dev Type: `Boolean`
Default: `false` Enable "dev" mode, which disables/skips caching. Instead, `sirv` will traverse the file system ***on every request***. Additionally, `dev` mode will ignore `maxAge` and `immutable` as these options generate a production-oriented `Cache-Control` header value. > **Important:** Do not use `dev` mode in production! #### opts.etag Type: `Boolean`
Default: `false` Generate and attach an `ETag` header to responses. > **Note:** If an incoming request's [`If-None-Match` header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-None-Match) matches the `ETag` value, a `304` response is given. #### opts.dotfiles Type: `Boolean`
Default: `false` Allow requests to dotfiles (files or directories beginning with a `.`). > **Note:** Requests to [`/.well-known/*`](https://tools.ietf.org/html/rfc8615) are always allowed. #### opts.extensions Type: `Array`
Default: `['html', 'htm']` The file extension fallbacks to check for if a pathame is not initially found. For example, if a `/login` request cannot find a `login` filename, it will then look for `login.html` and `login.htm` before giving up~! > **Important:** Actually, `sirv` will **also** look for `login/index.html` and `login/index.htm` before giving up. #### opts.gzip Type: `Boolean`
Default: `false` Determine if `sirv` look for **precompiled** `*.gz` files.
Must be enabled _and_ the incoming request's [`Accept Encoding`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding) must include "gzip" in order for `sirv` to search for the gzip'd alternative. > **Note:** The `.gz` assumption also applies to the `opts.extensions` list. ```js // NOTE: PSEUDO CODE // Showing lookup logic // Request: [Accept-Encoding: gzip] "/foobar.jpg" lookup([ '/foobar.jpg.gz', '/foobar.jpg', '/foobar.jpg.html.gz', '/foobar.jpg/index.html.gz', '/foobar.jpg.htm.gz', '/foobar.jpg/index.htm.gz', '/foobar.jpg.html', '/foobar.jpg/index.html', '/foobar.jpg.htm', '/foobar.jpg/index.htm', ]); // Request: [Accept-Encoding: gzip] "/" lookup([ '/index.html.gz', '/index.htm.gz', '/index.html', '/index.htm', ]); ``` #### opts.brotli Type: `Boolean`
Default: `false` Determine if `sirv` look for **precompiled** `*.br` files.
Must be enabled _and_ the incoming request's [`Accept Encoding`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding) must include either "br" or "brotli" in order for `sirv` to search for the brotli-compressed alternative. > **Note:** The `.br` assumption also applies to the `opts.extensions` list. When both `opts.broli` and `opts.gzip` are enabled — and all conditions are equal — then the brotli variant always takes priority. ```js // NOTE: PSEUDO CODE // Showing lookup logic // Request: [Accept-Encoding: br] "/foobar.jpg" lookup([ '/foobar.jpg.br', '/foobar.jpg', '/foobar.jpg.html.br', '/foobar.jpg/index.html.br', '/foobar.jpg.htm.br', '/foobar.jpg/index.htm.br', '/foobar.jpg.html', '/foobar.jpg/index.html', '/foobar.jpg.htm', '/foobar.jpg/index.htm', ]); // Request: [Accept-Encoding: br,gz] "/" lookup([ '/index.html.br' '/index.htm.br' '/index.html.gz' '/index.htm.gz' '/index.html' '/index.htm' ]); ``` #### opts.maxAge Type: `Number`
Default: `undefined` Enables the `Cache-Control` header on responses and sets the `max-age` value (in seconds).
For example, `maxAge: 31536000` is equivalent to one year. #### opts.immutable Type: `Boolean`
Default: `false` Appends the [`immutable` directive](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control#Revalidation_and_reloading) on your `Cache-Control` header, used for uniquely-named assets that will not change! > **Important:** Will only work if `opts.maxAge` has a value defined! #### opts.single Type: `Boolean` or `String`
Default: `false` Treat the directory as a single-page application. When `true`, the directory's index page (default `index.html`) will be sent if the request asset does not exist.
You may pass a `string` value to use a file _instead of_ `index.html` as your fallback. For example, if "/about" is requested but no variants of that file exist, then the response for "/" is sent instead: ```js // Note: This is psuedo code to illustrate what's happening // Request: "/about" let file = find(['/about', '/about.html', '/about.htm', '/about/index.html', '/about.htm']); if (file) { send(file); } else if (opts.single === true) { file = find(['/', '/index.html', '/index.htm']); send(file); } else if (typeof opts.single === 'string') { file = find([opts.single]); send(file); } else { // next() or 404 } ``` #### opts.ignores Type: `false` or `Array` Specify paths/patterns that should ignore the fallback behavior that `opts.single` provides. By default, any asset-like path (URLs that end with an extension) will be ignored. This means that, for example, if `/foobar.jpg` is not found, a `404` response is sent instead of the `index.html` fallback. Additionally, any `/.well-known/*` pathname ignores the fallback – as do all other dotfile requests when `opts.dotfiles` is enabled. Any string value(s) will be passed through `new RegExp(value, 'i')` directly. Finally, you may set `ignores: false` to disable ***all*** ignores, including the defaults. Put differently, this will fallback ***all*** unknown pathnames to your `index.html` (or custom `opts.single` value). > **Important:** Only has an effect if `opts.single` is enabled. #### opts.onNoMatch Type: `Function` A custom function to run if a file cannot be found for a given request.
By default, `sirv` will send a basic `(404) Not found` response. The function receives the current `req , res ` pair for as its two arguments. > **Note:** This won't run if a `next` callback has been provided to the middleware; see [`sirv`](#sirvdir-opts) description. #### opts.setHeaders Type: `Function` A custom function to append or change any headers on the outgoing response. There is no default. Its signature is `(res, pathname, stats)`, where `res` is the `ServerResponse`, `pathname` is incoming request path (stripped of queries), and `stats` is the file's result from [`fs.statSync`](https://nodejs.org/api/fs.html#fs_fs_statsync_path). ## License MIT © [Luke Edwards](https://lukeed.com)

c	File Name	Size	T	Date
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-	package.json	571	json	2026-04-22 12:54:07
-	readme.md	8964	md	2026-04-22 12:54:07
-	sirv.d.ts	800	ts	2026-04-22 12:54:07

🌲 / mnt pelican docker rootfs overlayfs 35e8d9b717682b72db2f62a2b1eeab1abbe9a93a29c3b59ec67ecc072a950e48 app frontend node_modules sirv

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