Make uint8ArrayToString also accept an ArrayBuffer

Fixes #14

index.d.ts

@@ -144,7 +144,7 @@ console.log(uint8ArrayToString(ja, 'shift-jis'));
 //=> 'こんにちは'
 ```
 */
-export function uint8ArrayToString(array: Uint8Array, encoding?: string): string;
+export function uint8ArrayToString(array: Uint8Array | ArrayBuffer, encoding?: string): string;
 
 /**
 Convert a string to a `Uint8Array` (using UTF-8 encoding).

index.js

@@ -1,16 +1,29 @@
 const objectToString = Object.prototype.toString;
 const uint8ArrayStringified = '[object Uint8Array]';
+const arrayBufferStringified = '[object ArrayBuffer]';
 
-export function isUint8Array(value) {
+function isType(value, typeConstructor, typeStringified) {
 	if (!value) {
 		return false;
 	}
 
-	if (value.constructor === Uint8Array) {
+	if (value.constructor === typeConstructor) {
 		return true;
 	}
 
-	return objectToString.call(value) === uint8ArrayStringified;
+	return objectToString.call(value) === typeStringified;
+}
+
+export function isUint8Array(value) {
+	return isType(value, Uint8Array, uint8ArrayStringified);
+}
+
+function isArrayBuffer(value) {
+	return isType(value, ArrayBuffer, arrayBufferStringified);
+}
+
+function isUint8ArrayOrArrayBuffer(value) {
+	return isUint8Array(value) || isArrayBuffer(value);
 }
 
 export function assertUint8Array(value) {
@@ -19,6 +32,12 @@ export function assertUint8Array(value) {
 	}
 }
 
+export function assertUint8ArrayOrArrayBuffer(value) {
+	if (!isUint8ArrayOrArrayBuffer(value)) {
+		throw new TypeError(`Expected \`Uint8Array\` or \`ArrayBuffer\`, got \`${typeof value}\``);
+	}
+}
+
 export function toUint8Array(value) {
 	if (value instanceof ArrayBuffer) {
 		return new Uint8Array(value);
@@ -95,7 +114,7 @@ const cachedDecoders = {
 };
 
 export function uint8ArrayToString(array, encoding = 'utf8') {
-	assertUint8Array(array);
+	assertUint8ArrayOrArrayBuffer(array);
 	cachedDecoders[encoding] ??= new globalThis.TextDecoder(encoding);
 	return cachedDecoders[encoding].decode(array);
 }

readme.md

@@ -130,7 +130,7 @@ const array3 = new Uint8Array([7, 8, 9]);
 //=> [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
 ```
 
-### `uint8ArrayToString(array: Uint8Array, encoding?: string = 'utf8'): string`
+### `uint8ArrayToString(array: Uint8Array | ArrayBuffer, encoding?: string = 'utf8'): string`
 
 Convert a `Uint8Array` to a string.
 

test.js

@@ -136,6 +136,11 @@ test('uint8ArrayToString with encoding', t => {
 	]), 'shift-jis'), 'こんにちは');
 });
 
+test('uint8ArrayToString with ArrayBuffer', t => {
+	const fixture = new Uint8Array([72, 101, 108, 108, 111]).buffer;
+	t.is(uint8ArrayToString(fixture), 'Hello');
+});
+
 test('uint8ArrayToBase64 and base64ToUint8Array', t => {
 	const fixture = stringToUint8Array('Hello');
 	const base64 = uint8ArrayToBase64(fixture);