Fix charset decoding for text bodies - #754
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Use Node's WHATWG TextDecoder for charsets it supports so text bodies follow Encoding Standard mappings, while keeping iconv-lite as the fallback for legacy encodings such as generic utf-16 and utf-32. Add regression coverage for windows-1252 C1 controls and invalid UTF-16 surrogate pairs. Fixes expressjs#680 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
bjohansebas
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Aug 2, 2026
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I actually recommend upgrading to the latest version of raw-body instead of using iconv-lite. It also lets you override the TextDecoder, as raw-body now does, in case anyone needs support for UTF-7 or other custom encodings.
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Fixes #680
Reproduction
A
text/plain; charset=windows-1252request containing bytes80 81 82 83 8d 9e 9fdecoded to€�‚ƒ�žŸ, replacing C1 control mappings at0x81and0x8d. Atext/plain; charset=utf-16lerequest containing two unpaired high surrogates decoded to a non-well-formed JavaScript string instead of replacement characters.Root cause
raw-body/iconv-litedecoding is used for request character sets. For encodings covered by the WHATWG Encoding Standard, that can differ from the platformTextDecodermappings and UTF-16 replacement behavior available in supported Node.js versions.Fix
Read parser bodies as bytes, then decode with Node's WHATWG
TextDecoderwhen it supports the charset. Keepiconv-liteas the fallback for legacy charsets thatTextDecoderdoes not support, and keep genericutf-16on the existing iconv-lite path to preserve current BOM-based behavior.Compatibility notes
This intentionally changes decoded text for WHATWG-supported charset labels to match
TextDecoder; unsupported labels and existingutf-16/utf-32behavior continue throughiconv-lite.Validation
npx mocha --reporter spec --check-leaks test\text.js --grep "windows-1252|utf-16"-> 0 passing, 2 failing.npm test-> 271 passing.npm run lint-> passed.