FileReader

HTML5 FileAPI FileReader for Node.JS (could potentially be modified to work with older browsers as well).

See https://github.com/node-file-api/file-api and https://developer.mozilla.org/en-US/docs/Web/API/FileReader

'use strict';

var FileReader = require('filereader')
  , 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) {
  console.log("dataUrlSize:", ev.target.result.length);
});

// `onloadend` as property
fileReader.onloadend', function () {
  console.log("Success");
});

Implemented API

• .readAsArrayBuffer(<File>)
• .readAsBinaryString(<File>)
• .readAsDataURL(<File>)
• .readAsText(<File>)
• .addEventListener(eventname, callback)
• .removeEventListener(callback)
• .dispatchEvent(eventname)
• .EMPTY = 0
• .LOADING = 1
• .DONE = 2
• .error = undefined
• .readyState = self.EMPTY
• .result = undefined

Events

• start
• progress
• error
• load
• end
• abort
• data // non-standard

Event Payload

end

{ target:
  { nodeBufferResult: <Buffer> // non-standard
  , result: <Buffer|Binary|Text|DataURL>
  }
}

progress

// fs.stat will probably complete before this
// but possibly it will not, hence the check
{ lengthComputable: (!isNaN(file.size)) ? true : false
, loaded: buffers.dataLength
, total: file.size
}

Non-W3C API

• .on(eventname, callback)
• .nodeChunkedEncoding = false
• .setNodeChunkedEncoding(<Boolean>)

Misc Notes on FileReader

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

EventTarget.target.nodeBufferResult 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.