source: node_modules/serve-static/README.md

# serve-static

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## Install

This is a [Node.js](https://nodejs.org/en/) module available through the
[npm registry](https://www.npmjs.com/). Installation is done using the
[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally):

```sh
$ npm install serve-static
```

## API

```js
var serveStatic = require('serve-static')
```

### serveStatic(root, options)

Create a new middleware function to serve files from within a given root
directory. The file to serve will be determined by combining `req.url`
with the provided root directory. When a file is not found, instead of
sending a 404 response, this module will instead call `next()` to move on
to the next middleware, allowing for stacking and fall-backs.

#### Options

##### acceptRanges

Enable or disable accepting ranged requests, defaults to true.
Disabling this will not send `Accept-Ranges` and ignore the contents
of the `Range` request header.

##### cacheControl

Enable or disable setting `Cache-Control` response header, defaults to
true. Disabling this will ignore the `immutable` and `maxAge` options.

##### dotfiles

 Set how "dotfiles" are treated when encountered. A dotfile is a file
or directory that begins with a dot ("."). Note this check is done on
the path itself without checking if the path actually exists on the
disk. If `root` is specified, only the dotfiles above the root are
checked (i.e. the root itself can be within a dotfile when set
to "deny").

  - `'allow'` No special treatment for dotfiles.
  - `'deny'` Deny a request for a dotfile and 403/`next()`.
  - `'ignore'` Pretend like the dotfile does not exist and 404/`next()`.

The default value is similar to `'ignore'`, with the exception that this
default will not ignore the files within a directory that begins with a dot.

##### etag

Enable or disable etag generation, defaults to true.

##### extensions

Set file extension fallbacks. When set, if a file is not found, the given
extensions will be added to the file name and search for. The first that
exists will be served. Example: `['html', 'htm']`.

The default value is `false`.

##### fallthrough

Set the middleware to have client errors fall-through as just unhandled
requests, otherwise forward a client error. The difference is that client
errors like a bad request or a request to a non-existent file will cause
this middleware to simply `next()` to your next middleware when this value
is `true`. When this value is `false`, these errors (even 404s), will invoke
`next(err)`.

Typically `true` is desired such that multiple physical directories can be
mapped to the same web address or for routes to fill in non-existent files.

The value `false` can be used if this middleware is mounted at a path that
is designed to be strictly a single file system directory, which allows for
short-circuiting 404s for less overhead. This middleware will also reply to
all methods.

The default value is `true`.

##### immutable

Enable or disable the `immutable` directive in the `Cache-Control` response
header, defaults to `false`. If set to `true`, the `maxAge` option should
also be specified to enable caching. The `immutable` directive will prevent
supported clients from making conditional requests during the life of the
`maxAge` option to check if the file has changed.

##### index

By default this module will send "index.html" files in response to a request
on a directory. To disable this set `false` or to supply a new index pass a
string or an array in preferred order.

##### lastModified

Enable or disable `Last-Modified` header, defaults to true. Uses the file
system's last modified value.

##### maxAge

Provide a max-age in milliseconds for http caching, defaults to 0. This
can also be a string accepted by the [ms](https://www.npmjs.org/package/ms#readme)
module.

##### redirect

Redirect to trailing "/" when the pathname is a dir. Defaults to `true`.

##### setHeaders

Function to set custom headers on response. Alterations to the headers need to
occur synchronously. The function is called as `fn(res, path, stat)`, where
the arguments are:

  - `res` the response object
  - `path` the file path that is being sent
  - `stat` the stat object of the file that is being sent

## Examples

### Serve files with vanilla node.js http server

```js
var finalhandler = require('finalhandler')
var http = require('http')
var serveStatic = require('serve-static')

// Serve up public/ftp folder
var serve = serveStatic('public/ftp', { index: ['index.html', 'index.htm'] })

// Create server
var server = http.createServer(function onRequest (req, res) {
  serve(req, res, finalhandler(req, res))
})

// Listen
server.listen(3000)
```

### Serve all files as downloads

```js
var contentDisposition = require('content-disposition')
var finalhandler = require('finalhandler')
var http = require('http')
var serveStatic = require('serve-static')

// Serve up public/ftp folder
var serve = serveStatic('public/ftp', {
  index: false,
  setHeaders: setHeaders
})

// Set header to force download
function setHeaders (res, path) {
  res.setHeader('Content-Disposition', contentDisposition(path))
}

// Create server
var server = http.createServer(function onRequest (req, res) {
  serve(req, res, finalhandler(req, res))
})

// Listen
server.listen(3000)
```

### Serving using express

#### Simple

This is a simple example of using Express.

```js
var express = require('express')
var serveStatic = require('serve-static')

var app = express()

app.use(serveStatic('public/ftp', { index: ['default.html', 'default.htm'] }))
app.listen(3000)
```

#### Multiple roots

This example shows a simple way to search through multiple directories.
Files are searched for in `public-optimized/` first, then `public/` second
as a fallback.

```js
var express = require('express')
var path = require('path')
var serveStatic = require('serve-static')

var app = express()

app.use(serveStatic(path.join(__dirname, 'public-optimized')))
app.use(serveStatic(path.join(__dirname, 'public')))
app.listen(3000)
```

#### Different settings for paths

This example shows how to set a different max age depending on the served
file type. In this example, HTML files are not cached, while everything else
is for 1 day.

```js
var express = require('express')
var path = require('path')
var serveStatic = require('serve-static')

var app = express()

app.use(serveStatic(path.join(__dirname, 'public'), {
  maxAge: '1d',
  setHeaders: setCustomCacheControl
}))

app.listen(3000)

function setCustomCacheControl (res, path) {
  if (serveStatic.mime.lookup(path) === 'text/html') {
    // Custom Cache-Control for HTML files
    res.setHeader('Cache-Control', 'public, max-age=0')
  }
}
```

## License

[MIT](LICENSE)

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