Dbqb_Study/吴光慧学习笔记/11.1/study/node_modules/send/README.md

# send

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Send is a library for streaming files from the file system as a 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.

Looking to serve up entire folders mapped to URLs? Try [serve-static](https://www.npmjs.org/package/serve-static).

## 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 send
```

## API

```js
var send = require('send')
```

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

Create a new `SendStream` 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.

##### 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 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.

##### 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.

#### Events

The `SendStream` is an event emitter and will emit the following events:

  - `error` an error occurred `(err)`
  - `directory` a directory was requested `(res, path)`
  - `file` a file was requested `(path, stat)`
  - `headers` the headers are about to be set on a file `(res, path, stat)`
  - `stream` file streaming has started `(stream)`
  - `end` streaming has completed

#### .pipe

The `pipe` method is used to pipe the response into the Node.js HTTP response
object, typically `send(req, path, options).pipe(res)`.

### .mime

The `mime` export is the global instance of 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).

## Error-handling

By default when no `error` listeners are present an automatic response will be
made, otherwise you have full control over the response, aka you may show a 5xx
page etc.

## 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 __DEBUG__:

```
$ 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
var http = require('http')
var send = require('send')

var server = http.createServer(function onRequest (req, res) {
  send(req, '/path/to/index.html')
    .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
var http = require('http')
var parseUrl = require('parseurl')
var send = require('send')

var server = http.createServer(function onRequest (req, res) {
  send(req, parseUrl(req).pathname, { root: '/www/public' })
    .pipe(res)
})

server.listen(3000)
```

### Custom file types

```js
var http = require('http')
var parseUrl = require('parseurl')
var send = require('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']
})

var server = http.createServer(function onRequest (req, res) {
  send(req, parseUrl(req).pathname, { root: '/www/public' })
    .pipe(res)
})

server.listen(3000)
```

### Custom directory index view

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

```js
var http = require('http')
var fs = require('fs')
var parseUrl = require('parseurl')
var send = require('send')

// Transfer arbitrary files from within /www/example.com/public/*
// with a custom handler for directory listing
var server = http.createServer(function onRequest (req, res) {
  send(req, parseUrl(req).pathname, { index: false, root: '/www/public' })
    .once('directory', directory)
    .pipe(res)
})

server.listen(3000)

// Custom directory handler
function directory (res, path) {
  var stream = this

  // redirect to trailing slash for consistent url
  if (!stream.hasTrailingSlash()) {
    return stream.redirect(path)
  }

  // get directory list
  fs.readdir(path, function onReaddir (err, list) {
    if (err) return stream.error(err)

    // render an index for the directory
    res.setHeader('Content-Type', 'text/plain; charset=UTF-8')
    res.end(list.join('\n') + '\n')
  })
}
```

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

```js
var http = require('http')
var parseUrl = require('parseurl')
var send = require('send')

var server = http.createServer(function onRequest (req, res) {
  // your custom error-handling logic:
  function error (err) {
    res.statusCode = err.status || 500
    res.end(err.message)
  }

  // your custom headers
  function headers (res, path, stat) {
    // serve all files for download
    res.setHeader('Content-Disposition', 'attachment')
  }

  // your custom directory handling logic:
  function redirect () {
    res.statusCode = 301
    res.setHeader('Location', req.url + '/')
    res.end('Redirecting to ' + req.url + '/')
  }

  // transfer arbitrary files from within
  // /www/example.com/public/*
  send(req, parseUrl(req).pathname, { root: '/www/public' })
    .on('error', error)
    .on('directory', redirect)
    .on('headers', headers)
    .pipe(res)
})

server.listen(3000)
```

## License

[MIT](LICENSE)

[appveyor-image]: https://badgen.net/appveyor/ci/dougwilson/send/master?label=windows
[appveyor-url]: https://ci.appveyor.com/project/dougwilson/send
[coveralls-image]: https://badgen.net/coveralls/c/github/pillarjs/send/master
[coveralls-url]: https://coveralls.io/r/pillarjs/send?branch=master
[github-actions-ci-image]: https://badgen.net/github/checks/pillarjs/send/master?label=linux
[github-actions-ci-url]: https://github.com/pillarjs/send/actions/workflows/ci.yml
[node-image]: https://badgen.net/npm/node/send
[node-url]: https://nodejs.org/en/download/
[npm-downloads-image]: https://badgen.net/npm/dm/send
[npm-url]: https://npmjs.org/package/send
[npm-version-image]: https://badgen.net/npm/v/send