@@ -0,0 +1,29 @@
+import { describe, it, expect } from 'vitest';
+import { TextDecoder, TextEncoder } from './text-common';
+
+describe('TextDecoder', () => {
+	const decoder = new TextDecoder();
+
+	it('decodes an ArrayBuffer', () => {
+		expect(decoder.decode(new Uint8Array([0x68, 0x69]).buffer)).toBe('hi');
+	});
+
+	it('decodes only the bytes inside a typed array view', () => {
+		const bytes = new Uint8Array([0x78, 0x78, 0x68, 0x69, 0x78]);
+		expect(decoder.decode(bytes.subarray(2, 4))).toBe('hi');
+	});
+
+	it('decodes only the bytes inside a DataView', () => {
+		const bytes = new Uint8Array([0x78, 0x68, 0x69, 0x78]);
+		expect(decoder.decode(new DataView(bytes.buffer, 1, 2))).toBe('hi');
+	});
+
+	it('round-trips multi-byte characters through TextEncoder', () => {
+		const encoded = new TextEncoder().encode('héllo ✓');
+		expect(decoder.decode(encoded)).toBe('héllo ✓');
+	});
+
+	it('rejects values that are not buffers', () => {
+		expect(() => decoder.decode('abc' as any)).toThrow();
+	});
+});
@@ -71,7 +71,7 @@ export class TextDecoder {
 		if (Object_prototype_toString.call(buffer) !== ArrayBufferString) {
 			throw Error("Failed to execute 'decode' on 'TextDecoder': The provided value is not of type '(ArrayBuffer or ArrayBufferView)'");
 		}
-		const inputAs8 = new Uint8Array(buffer);
+		const inputAs8 = ArrayBuffer.isView(input) ? new Uint8Array(input.buffer, input.byteOffset, input.byteLength) : new Uint8Array(buffer);
 		let resultingString = '';
 		for (let index = 0, len = inputAs8.length | 0; index < len; index = (index + 32768) | 0) {
 			resultingString += String.fromCharCode.apply(0, inputAs8.slice(index, (index + 32768) | 0));
Original file line number	Diff line number	Diff line change
`@@ -71,7 +71,7 @@ export class TextDecoder {`
`71`	`71`	`if (Object_prototype_toString.call(buffer) !== ArrayBufferString) {`
`72`	`72`	`throw Error("Failed to execute 'decode' on 'TextDecoder': The provided value is not of type '(ArrayBuffer or ArrayBufferView)'");`
`73`	`73`	`}`
`74`		`- const inputAs8 = new Uint8Array(buffer);`
	`74`	`+ const inputAs8 = ArrayBuffer.isView(input) ? new Uint8Array(input.buffer, input.byteOffset, input.byteLength) : new Uint8Array(buffer);`
`75`	`75`	`let resultingString = '';`
`76`	`76`	`for (let index = 0, len = inputAs8.length \| 0; index < len; index = (index + 32768) \| 0) {`
`77`	`77`	`resultingString += String.fromCharCode.apply(0, inputAs8.slice(index, (index + 32768) \| 0));`