content-disposition

What is content-disposition?

The content-disposition npm package is used to create and parse HTTP Content-Disposition headers. It is commonly used to set the disposition type (inline or attachment) and parameters for a response in a web application, which instructs the browser how to handle the content, such as to display it inline or to download it as a file.

What are content-disposition's main functionalities?

Creating Content-Disposition header for attachment

This code sample demonstrates how to create a Content-Disposition header for an attachment, suggesting the browser to download the file as 'filename.txt'.

const contentDisposition = require('content-disposition');
let header = contentDisposition('filename.txt');

Creating Content-Disposition header with Unicode filenames

This code sample shows how to create a Content-Disposition header for a file with a Unicode filename, ensuring proper encoding for non-ASCII characters.

const contentDisposition = require('content-disposition');
let header = contentDisposition('filename.txt', { type: 'attachment', filename: 'файл.txt' });

Parsing Content-Disposition header

This code sample illustrates how to parse a Content-Disposition header string to get an object representing the disposition type and parameters.

const contentDisposition = require('content-disposition');
let parsedHeader = contentDisposition.parse('attachment; filename="filename.txt"');

Other packages similar to content-disposition

mime

The 'mime' package can be used to determine a file's MIME type based on its extension, which is helpful when setting the Content-Type header. It does not directly handle Content-Disposition headers but is often used in conjunction with setting these headers.

form-data

The 'form-data' package allows for the creation and submission of FormData instances, which can include files with specific Content-Disposition. It is more focused on constructing multipart/form-data payloads than on creating or parsing Content-Disposition headers.

README

content-disposition

Create and parse HTTP Content-Disposition header

Installation

$ npm install content-disposition

API

var contentDisposition = require('content-disposition')

contentDisposition(filename, options)

Create an attachment Content-Disposition header value using the given file name, if supplied. The filename is optional and if no file name is desired, but you want to specify options, set filename to undefined.

res.setHeader('Content-Disposition', contentDisposition('∫ maths.pdf'))

note HTTP headers are of the ISO-8859-1 character set. If you are writing this header through a means different from setHeader in Node.js, you'll want to specify the 'binary' encoding in Node.js.

Options

contentDisposition accepts these properties in the options object.

fallback

If the filename option is outside ISO-8859-1, then the file name is actually stored in a supplemental field for clients that support Unicode file names and a ISO-8859-1 version of the file name is automatically generated.

This specifies the ISO-8859-1 file name to override the automatic generation or disables the generation all together, defaults to true.

• A string will specify the ISO-8859-1 file name to use in place of automatic generation.
• false will disable including a ISO-8859-1 file name and only include the Unicode version (unless the file name is already ISO-8859-1).
• true will enable automatic generation if the file name is outside ISO-8859-1.

If the filename option is ISO-8859-1 and this option is specified and has a different value, then the filename option is encoded in the extended field and this set as the fallback field, even though they are both ISO-8859-1.

type

Specifies the disposition type, defaults to "attachment". This can also be "inline", or any other value (all values except inline are treated like attachment, but can convey additional information if both parties agree to it). The type is normalized to lower-case.

contentDisposition.parse(string)

var disposition = contentDisposition.parse('attachment; filename="EURO rates.txt"; filename*=UTF-8\'\'%e2%82%ac%20rates.txt')

Parse a Content-Disposition header string. This automatically handles extended ("Unicode") parameters by decoding them and providing them under the standard parameter name. This will return an object with the following properties (examples are shown for the string 'attachment; filename="EURO rates.txt"; filename*=UTF-8\'\'%e2%82%ac%20rates.txt'):

• type: The disposition type (always lower case). Example: 'attachment'

• parameters: An object of the parameters in the disposition (name of parameter always lower case and extended versions replace non-extended versions). Example: {filename: "€ rates.txt"}

Examples

Send a file for download

var contentDisposition = require('content-disposition')
var destroy = require('destroy')
var fs = require('fs')
var http = require('http')
var onFinished = require('on-finished')

var filePath = '/path/to/public/plans.pdf'

http.createServer(function onRequest (req, res) {
  // set headers
  res.setHeader('Content-Type', 'application/pdf')
  res.setHeader('Content-Disposition', contentDisposition(filePath))

  // send file
  var stream = fs.createReadStream(filePath)
  stream.pipe(res)
  onFinished(res, function () {
    destroy(stream)
  })
})

Testing

$ npm test

References

• RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1
• RFC 5987: Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters
• RFC 6266: Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)
• Test Cases for HTTP Content-Disposition header field (RFC 6266) and the Encodings defined in RFCs 2047, 2231 and 5987

License

MIT