npm package: @fastify/send
Description: Better streaming static file server with Range and conditional-GET support
Author: TJ Holowaychuk
Latest version: 4.1.0

# @fastify/send

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Send is a library for streaming files from the file system as an HTTP response
supporting partial responses (Ranges), conditional-GET negotiation (If-Match,
If-Unmodified-Since, If-None-Match, If-Modified-Since), high test coverage,
and granular events which may be leveraged to take appropriate actions in your
application or framework.

## Installation

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):

```bash
$ npm install @fastify/send
```

### TypeScript

`@types/mime@3` must be used if wanting to use TypeScript;
`@types/mime@4` removed the `mime` types.

```bash
$ npm install -D @types/mime@3
```

## API

```js
const send = require('@fastify/send')
```

### send(req, path, [options])

Provide `statusCode`, `headers`, and `stream` for the given path to send to a
`res`. The `req` is the Node.js HTTP request and the `path `is a urlencoded path
to send (urlencoded, not the actual file-system path).

#### 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.

##### contentType

By default, this library uses the `mime` module to set the `Content-Type`
of the response based on the file extension of the requested file.

To disable this functionality, set `contentType` to `false`.
The `Content-Type` header will need to be set manually if disabled.

##### 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 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'` Send a 403 for any request for a dotfile.
  - `'ignore'` Pretend like the dotfile does not exist and 404.

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, for backward-compatibility.

##### end

Byte offset at which the stream ends, defaults to the length of the file
minus 1. The end is inclusive in the stream, meaning `end: 3` will include
the 4th byte in the stream.

##### etag

Enable or disable etag generation, defaults to true.

##### extensions

If a given file doesn't exist, try appending one of the given extensions,
in the given order. By default, this is disabled (set to `false`). An
example value that will serve extension-less HTML files: `['html', 'htm']`.
This is skipped if the requested file already has an extension.

##### 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 send supports "index.html" files, 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.

##### maxContentRangeChunkSize

Specify the maximum response content size, defaults to the entire file size.
This will be used when `acceptRanges` is true.

##### root

Serve files relative to `path`.

##### start

Byte offset at which the stream starts, defaults to 0. The start is inclusive,
meaning `start: 2` will include the 3rd byte in the stream.

##### highWaterMark

When provided, this option sets the maximum number of bytes that the internal 
buffer will hold before pausing reads from the underlying resource.
If you omit this option (or pass undefined), Node.js falls back to 
its built-in default for readable binary streams.

### .mime

The `mime` export is the global instance of the
[`mime` npm module](https://www.npmjs.com/package/mime).

This is used to configure the MIME types that are associated with file extensions
as well as other options for how to resolve the MIME type of a file (like the
default type to use for an unknown file extension).

## Caching

It does _not_ perform internal caching, you should use a reverse proxy cache
such as Varnish for this, or those fancy things called CDNs. If your
application is small enough that it would benefit from single-node memory
caching, it's small enough that it does not need caching at all ;).

## Debugging

To enable `debug()` instrumentation output export __NODE_DEBUG__:

```
$ NODE_DEBUG=send node app
```

## Running tests

```
$ npm install
$ npm test
```

## Examples

### Serve a specific file

This simple example will send a specific file to all requests.

```js
const http = require('node:http')
const send = require('send')

const server = http.createServer(async function onRequest (req, res) {
  const { statusCode, headers, stream } = await send(req, '/path/to/index.html')
  res.writeHead(statusCode, headers)
  stream.pipe(res)
})

server.listen(3000)
```

### Serve all files from a directory

This simple example will just serve up all the files in a
given directory as the top-level. For example, a request
`GET /foo.txt` will send back `/www/public/foo.txt`.

```js
const http = require('node:http')
const parseUrl = require('parseurl')
const send = require('@fastify/send')

const server = http.createServer(async function onRequest (req, res) {
  const { statusCode, headers, stream } = await send(req, parseUrl(req).pathname, { root: '/www/public' })
  res.writeHead(statusCode, headers)
  stream.pipe(res)
})

server.listen(3000)
```

### Custom file types

```js
const http = require('node:http')
const parseUrl = require('parseurl')
const send = require('@fastify/send')

// Default unknown types to text/plain
send.mime.default_type = 'text/plain'

// Add a custom type
send.mime.define({
  'application/x-my-type': ['x-mt', 'x-mtt']
})

const server = http.createServer(function onRequest (req, res) {
  const { statusCode, headers, stream } = await send(req, parseUrl(req).pathname, { root: '/www/public' })
  res.writeHead(statusCode, headers)
  stream.pipe(res)
})

server.listen(3000)
```

### Custom directory index view

This is an example of serving up a structure of directories with a
custom function to render a listing of a directory.

```js
const http = require('node:http')
const fs = require('node:fs')
const parseUrl = require('parseurl')
const send = require('@fastify/send')

// Transfer arbitrary files from within /www/example.com/public/*
// with a custom handler for directory listing
const server = http.createServer(async function onRequest (req, res) {
  const { statusCode, headers, stream, type, metadata } = await send(req, parseUrl(req).pathname, { index: false, root: '/www/public' })
  if(type === 'directory') {
    // get directory list
    const list = await readdir(metadata.path)
    // render an index for the directory
    res.writeHead(200, { 'Content-Type': 'text/plain; charset=utf-8' })
    res.end(list.join('\n') + '\n')
  } else {
    res.writeHead(statusCode, headers)
    stream.pipe(res)
  }
})

server.listen(3000)
```

### Serving from a root directory with custom error-handling

```js
const http = require('node:http')
const parseUrl = require('parseurl')
const send = require('@fastify/send')

const server = http.createServer(async function onRequest (req, res) {
  // transfer arbitrary files from within
  // /www/example.com/public/*
  const { statusCode, headers, stream, type, metadata } = await send(req, parseUrl(req).pathname, { root: '/www/public' })
  switch (type) {
    case 'directory': {
      // your custom directory handling logic:
      res.writeHead(301, {
        'Location': metadata.requestPath + '/'
      })
      res.end('Redirecting to ' + metadata.requestPath + '/')
      break
    }
    case 'error': {
      // your custom error-handling logic:
      res.writeHead(metadata.error.status ?? 500, {})
      res.end(metadata.error.message)
      break
    }
    default: {
      // your custom headers
      // serve all files for download
      res.setHeader('Content-Disposition', 'attachment')
      res.writeHead(statusCode, headers)
      stream.pipe(res)
    }
  }
})

server.listen(3000)
```

## License

Licensed under [MIT](./LICENSE).