HTML5 FileAPI for Node.js


HTML5 FileAPI implemented in Node.js

The goal here is to be able to use this in connection with jsdom to create test utilities, possibly scraping utilities, ultimately an API-driven browser written in Node.



npm install file-api


var FileAPI = require('file-api')
  , File = FileAPI.File
  , FileList = FileAPI.FileList
  , FileReader = FileAPI.FileReader


Since HTML5 FileAPI has been described by the W3C (terse, technical) and Mozilla Developer Center (understandable, end-user-oriented) in detail, I'll just highlight the differences:

  • File is not (yet) a subclass of Blob
  • FileError and FileException are not yet implemented (they use Error instead)
  • blob: scheme and remote URI schemes are not yet implemented

FormData on MDN

Has the special method setNodeChunkedEncoding()

In the browser, File has no constructor. In Node, it does.

node-mime is used for extension-based automatic ContentType detection (uses name if available, or path if not)


var file = new File("./files/myfile.txt");

File({ buffer: Node.Buffer })

var file = new File({ 
  name: "abc-song.txt",   // required
  type: "text/plain",     // optional
  buffer: new Buffer("abcdefg,hijklmnop, qrs, tuv, double-u, x, y and z")

File({ stream: Node.ReadStream })

var file = new File({
  name: "abc-song.txt",       // required
  type: "text/plain",         // optional
  stream: new EventEmitter()  // a read stream (emits `error`, `data`, `end`)

process.nextTick(function () {'data', "abcdefg,hijklmnop, qrs, tuv, double-u, x, y and z");'end');


var file = new File({
  path: "./files/myfile.txt",   // path of file to read

  buffer: Node.Buffer,          // use this Buffer instead of reading file

  stream: Node.ReadStream,      // use this ReadStream instead of reading file

  name: "SomeAwesomeFile.txt",  // optional when using `path`
                                // must be supplied when using `Node.Buffer` or `Node.ReadStream`

  type: "text/plain",           // generated based on the extension of `name` or `path`

  jsdom: true,                  // be DoM-like and immediately get `size` and `lastModifiedDate`
                                // [default: false]

  async: true,                  // use `fs.stat` instead of `fs.statSync` for getting 
                                // the `jsdom` info
                                // [default: false]

  lastModifiedDate: fileStat.mtime.toISOString(),

  size: fileStat.size || Buffer.length

FileReader.setNodeChunkedEncoding() is a non-standard method which hints that the FileReader should chunk if possible

I.E. The file will be sent with the header Transfer-Encoding: chunked

The default is false since many webservers do not correctly implement the standard correctly, and hence do not expect or accept Transfer-Encoding: chunked from clients.

FileReader.on is a non-standard alias of addEventListener is a non-standard property which is a Node.Buffer instance of the data.

FileReader.on('data', fn) is a non-standard event which passes a Node.Buffer chunk each time the progress event is fired.

var fileReader = new FileReader();

fileReader.setNodeChunkedEncoding(true || false);
fileReader.readAsDataURL(new File('./files/my-file.txt'));

// non-standard alias of `addEventListener` listening to non-standard `data` event
fileReader.on('data', function (data) {
  console.log("chunkSize:", data.length);

// `onload` as listener
fileReader.addEventListener('load', function (ev) {

// `onloadend` as property
fileReader.onloadend', function () {

The browser has no constructor for this. Node has two.

new FileList(f1, f2, ...)

var fileList = new FileList(file1, file2, file3);

new FileList([f1, f2])

var files = [
    new File('./files/blob.bin'),
    new File('./files/image.jpg'),
    new File('./files/readme.txt')

fileList = new FileList(files);

Formal Documentation


Mozilla Developer Center:


// HTML5 File URI should be implemented
//   will need non-ahr 301-handling requester not prevent circular dep
// File should be a subclass of Blob
// jsdom EventTarget //
//    target.result
// jsdom ProgressEvent //
//    lengthComputable
//    loaded
//    total
//    initProgressEvent