file-type

What is file-type?

The file-type npm package is used to detect the file type of a Buffer/Uint8Array/ArrayBuffer. It supports many file types including images, audio, video, fonts, and archive formats. It is particularly useful when the file extension is unknown or has been changed, as it checks the file signature against a list of known file types.

What are file-type's main functionalities?

Detecting file type from a Buffer

This feature allows you to detect the file type of a file by reading it into a Buffer and using the `fromBuffer` method to determine the file type.

const FileType = require('file-type');
const fs = require('fs');

(async () => {
  const buffer = fs.readFileSync('example.png');
  const fileType = await FileType.fromBuffer(buffer);
  console.log(fileType);
})();

Detecting file type from a stream

This feature allows you to detect the file type of a file by creating a readable stream and using the `fromStream` method to determine the file type.

const FileType = require('file-type');
const fs = require('fs');

(async () => {
  const stream = fs.createReadStream('example.png');
  const fileType = await FileType.fromStream(stream);
  console.log(fileType);
})();

Detecting file type from a file path

This feature allows you to detect the file type directly from a file path using the `fromFile` method.

const FileType = require('file-type');

(async () => {
  const fileType = await FileType.fromFile('example.png');
  console.log(fileType);
})();

Other packages similar to file-type

mmmagic

The 'mmmagic' package is an async libmagic binding for node.js for content type detection. It uses magic numbers to detect the file type, similar to file-type, but it requires libmagic to be installed on the system, which can be a downside compared to the pure JavaScript implementation of file-type.

buffer-type

The 'buffer-type' package is another module for detecting the content type of a Buffer. It is less popular and has fewer file signatures compared to file-type, which means it may not recognize as many file types.

file-signature

The 'file-signature' package allows for identifying file types by checking their magic number signature. It is similar to file-type but has a smaller set of supported file types and a simpler API.

README

file-type

Detect the file type of a Buffer/Uint8Array

The file type is detected by checking the magic number of the buffer.

Install

$ npm install --save file-type

Usage

Node.js

var readChunk = require('read-chunk'); // npm install read-chunk
var fileType = require('file-type');
var buffer = readChunk.sync('unicorn.png', 0, 262);

fileType(buffer);
//=> {ext: 'png', mime: 'image/png'}

or from a remote location:

var http = require('http');
var fileType = require('file-type');
var url = 'http://assets-cdn.github.com/images/spinners/octocat-spinner-32.gif';

http.get(url, function (res) {
	res.once('data', function (chunk) {
		res.destroy();
		console.log(fileType(chunk));
		//=> {ext: 'gif', mime: 'image/gif'}
	});
});

Browser

var xhr = new XMLHttpRequest();
xhr.open('GET', 'unicorn.png');
xhr.responseType = 'arraybuffer';

xhr.onload = function () {
	fileType(new Uint8Array(this.response));
	//=> {ext: 'png', mime: 'image/png'}
};

xhr.send();

API

fileType(buffer)

Returns an object (or null when no match) with:

• ext - one of the supported file types
• mime - the MIME type

buffer

Type: buffer (Node.js), uint8array

It only needs the first 262 bytes.

CLI

$ npm install --global file-type

$ file-type --help

  Usage
    file-type <filename>
    cat <filename> | file-type

  Example
    cat unicorn.png | file-type
    png

Supported file types

• jpg
• png
• gif
• webp
• tif
• bmp
• jxr
• psd
• zip
• tar
• rar
• gz
• bz2
• 7z
• mp4
• mkv
• webm
• mov
• avi
• mpg
• mp3
• m4a
• ogg
• flac
• wav
• pdf
• epub
• exe
• swf
• rtf

SVG isn't included as it requires the whole file to be read, but you can get it here.

PR welcome for additional commonly used file types.

License

MIT © Sindre Sorhus