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fix(core): TextDecoder decodes only the bytes of a typed array view #11578

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Merged
NathanWalker merged 1 commit into from
Oct 28, 2026
Merged

fix(core): TextDecoder decodes only the bytes of a typed array view #11578

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29 changes: 29 additions & 0 deletions packages/core/text/text-common.spec.ts
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Original file line number Diff line number Diff line change
@@ -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();
});
});
2 changes: 1 addition & 1 deletion packages/core/text/text-common.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -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));
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