file-type

Detect the file type of a Buffer/Uint8Array

file-type

Detect the file type of a Buffer/Uint8Array

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

$ npm install --save file-type
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'} 
    });
});
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();

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

Type: buffer (Node.js), uint8array

It only needs the first 262 bytes.

$ npm install --global file-type
$ file-type --help
 
  Usage
    file-type <filename>
    cat <filename> | file-type
 
  Example
    cat unicorn.png | file-type
    png
  • jpg
  • png
  • gif
  • webp
  • cr2
  • tif
  • bmp
  • jxr
  • psd
  • zip
  • tar
  • rar
  • gz
  • bz2
  • 7z
  • mp4
  • m4v
  • mid
  • mkv
  • webm
  • mov
  • avi
  • wmv
  • mpg
  • mp3
  • m4a
  • ogg
  • flac
  • wav
  • pdf
  • epub
  • exe
  • swf
  • rtf
  • woff
  • woff2
  • eot
  • ttf
  • otf
  • ico
  • flv
  • ps
  • xz
  • sqlite

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.

MIT © Sindre Sorhus