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

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

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

or from a remote location:

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

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

Browser

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

xhr.onload = () => {
    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 Uint8Array

It only needs the first 262 bytes.

Supported file types

• jpg
• png
• gif
• webp
• flif
• cr2
• tif
• bmp
• jxr
• psd
• zip
• tar
• rar
• gz
• bz2
• 7z
• dmg
• mp4
• m4v
• mid
• mkv
• webm
• mov
• avi
• wmv
• mpg
• mp3
• m4a
• ogg
• opus
• flac
• wav
• amr
• pdf
• epub
• exe
• swf
• rtf
• woff
• woff2
• eot
• ttf
• otf
• ico
• flv
• ps
• xz
• sqlite
• nes
• crx
• xpi
• cab
• deb
• ar
• rpm
• Z
• lz
• msi

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.

Related

• file-type-cli - CLI for this module

License

MIT © Sindre Sorhus