Allow ArrayBuffer as input

index.d.ts

@@ -115,7 +115,7 @@ declare namespace fileType {
 
 declare const fileType: {
 	/**
-	Detect the file type of a `Buffer`/`Uint8Array`. The file type is detected by checking the [magic number](https://en.wikipedia.org/wiki/Magic_number_(programming)#Magic_numbers_in_files) of the buffer.
+	Detect the file type of a `Buffer`/`Uint8Array`/`ArrayBuffer`. The file type is detected by checking the [magic number](https://en.wikipedia.org/wiki/Magic_number_(programming)#Magic_numbers_in_files) of the buffer.
 
 	@param buffer - It only needs the first `.minimumBytes` bytes. The exception is detection of `docx`, `pptx`, and `xlsx` which potentially requires reading the whole file.
 	@returns An object with the detected file type and MIME type or `null` when there was no match.
@@ -147,7 +147,7 @@ declare const fileType: {
 	});
 	```
 	*/
-	(buffer: Buffer | Uint8Array): fileType.FileTypeResult | null;
+	(buffer: Buffer | Uint8Array | ArrayBuffer): fileType.FileTypeResult | null;
 
 	/**
 	The minimum amount of bytes needed to detect a file type. Currently, it's 4100 bytes, but it can change, so don't hard-code it.

index.js

@@ -17,8 +17,8 @@ function readUInt64LE(buf, offset = 0) {
 }
 
 const fileType = input => {
-	if (!(input instanceof Uint8Array || Buffer.isBuffer(input))) {
-		throw new TypeError(`Expected the \`input\` argument to be of type \`Uint8Array\` or \`Buffer\`, got \`${typeof input}\``);
+	if (!(input instanceof Uint8Array || input instanceof ArrayBuffer || Buffer.isBuffer(input))) {
+		throw new TypeError(`Expected the \`input\` argument to be of type \`Uint8Array\` or \`Buffer\` or \`ArrayBuffer\`, got \`${typeof input}\``);
 	}
 
 	const buf = input instanceof Uint8Array ? input : new Uint8Array(input);

index.test-d.ts

@@ -5,6 +5,7 @@ import * as fs from 'fs';
 
 expectType<FileTypeResult | null>(fileType(new Buffer([0xff, 0xd8, 0xff])));
 expectType<FileTypeResult | null>(fileType(new Uint8Array([0xff, 0xd8, 0xff])));
+expectType<FileTypeResult | null>(fileType(new ArrayBuffer(42)));
 
 const result = fileType(new Buffer([0xff, 0xd8, 0xff]));
 if (result != null) {

package.json

@@ -1,7 +1,7 @@
 {
 	"name": "file-type",
 	"version": "10.10.0",
-	"description": "Detect the file type of a Buffer/Uint8Array",
+	"description": "Detect the file type of a Buffer/Uint8Array/ArrayBuffer",
 	"license": "MIT",
 	"repository": "sindresorhus/file-type",
 	"author": {

readme.md

@@ -1,6 +1,6 @@
 # file-type [![Build Status](https://travis-ci.org/sindresorhus/file-type.svg?branch=master)](https://travis-ci.org/sindresorhus/file-type)
 
-> Detect the file type of a Buffer/Uint8Array
+> Detect the file type of a Buffer/Uint8Array/ArrayBuffer
 
 The file type is detected by checking the [magic number](https://en.wikipedia.org/wiki/Magic_number_(programming)#Magic_numbers_in_files) of the buffer.
 
@@ -99,7 +99,7 @@ Or `null` when there is no match.
 
 #### input
 
-Type: `Buffer` `Uint8Array`
+Type: `Buffer | Uint8Array | ArrayBuffer`
 
 It only needs the first `.minimumBytes` bytes. The exception is detection of `docx`, `pptx`, and `xlsx` which potentially requires reading the whole file.
 

test.js

@@ -271,4 +271,8 @@ test('validate the input argument type', t => {
 	t.notThrows(() => {
 		fileType(new Uint8Array());
 	});
+
+	t.notThrows(() => {
+		fileType(new ArrayBuffer());
+	});
 });