@marklb/file-type NPM

file-type

Detect the file type of a Buffer/Uint8Array

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

This repository is a fork of sindresorhus/file-type with ES5 build. IE couldn't load the script and the projects using this package are not configured to transpile dependencies. Also started making a types file for typescript, but it isn't complete.

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, fileType.minimumBytes);

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, response => {
	response.on('readable', () => {
		const chunk = response.read(fileType.minimumBytes);
		response.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 types
mime - The MIME type

Or null when no match.

input

Type: Buffer Uint8Array

It only needs the first .minimumBytes bytes. The exception is detection of docx, pptx, and xlsx which potentially requires reading the whole file.