About this fork
This is a practice of writing in LiveScript. It is also a more compact and, because of that, at least in my opnion, more readable version of the original code. Once familiarized with the checker function it becomes clear, where exactly the magic number is in a file and what it really means.
The meaningful sequences of bytes are presented as simple strings. Moreover, the language features of LiveScript make the whole file more compact, so what is left is mostly list of file headers and some control patterns, the only information really needed while learning about the magic numbers of certain file types.
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 file-type
Usage
Node.js
const readChunk = require('read-chunk');
const fileType = require('file-type');
const buffer = readChunk.sync('unicorn.png', 0, 4100);
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(input)
Returns an Object with:
ext- One of the supported file typesmime- The MIME type
Or null when no match.
input
Type: Buffer Uint8Array
It only needs the first 4100 bytes.
Supported file types
jpgpnggifwebpflifcr2tifbmpjxrpsdziptarrargzbz27zdmgmp4m4vmidmkvwebmmovaviwmvmpgmp3m4aoggopusflacwavamrpdfepubmobi- Mobipocketexeswfrtfwoffwoff2eotttfotficoflvpsxzsqlitenescrxxpicabdebarrpmZlzmsimxfmtswasmblendbpgdocxpptxxlsx3gpjp2- JPEG 2000jpm- JPEG 2000jpx- JPEG 2000mj2- Motion JPEG 2000aifodt- OpenDocument for word processingods- OpenDocument for spreadsheetsodp- OpenDocument for presentationsxmlheic
SVG isn't included as it requires the whole file to be read, but you can get it here.
Pull request welcome for additional commonly used file types.
Related
- file-type-cli - CLI for this module
Created by
License
MIT