Encode JIS X 0212 characters with the standard 3-byte form - #63
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polygonplanet merged 1 commit intoAug 1, 2026
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The EUC-JP and ISO-2022-JP encoders consulted UTF8_TO_JIS_TABLE before UTF8_TO_JISX0212_TABLE. 280 JIS X 0212 code points are also duplicated in UTF8_TO_JIS_TABLE at rows unassigned by JIS X 0208, so they were emitted as a 2-byte code in those rows rather than the JIS X 0212 form, producing output that standard EUC-JP and ISO-2022-JP decoders reject. Fall through to the JIS X 0212 form (EUC-JP SS3 0x8F / ISO-2022-JP ESC $ ( D) whenever a code point is present in both tables.
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The EUC-JP and ISO-2022-JP encoders emit 280 JIS X 0212 characters in a non-standard 2-byte form that no standard decoder accepts. These code points are duplicated into
UTF8_TO_JIS_TABLEat rows unassigned by JIS X 0208, and that table is checked beforeUTF8_TO_JISX0212_TABLE, so the existing 3-byte path (encoding-convert.js:718) is never reached.For example U+4E28 encodes to
[0xF9,0xAD], which Python'seuc_jprejects, whereas the library's own decoder and the changelog's "Supports JIS X 0212:1990" expect[0x8F,0xB0,0xA9]:When a code point is present in both tables it now uses the JIS X 0212 form. The 280 affected characters occupy JIS X 0208 rows 13 and 89-92, which are all unassigned, so no genuine JIS X 0208 character is rerouted and Shift_JIS output is unchanged. Verified against Python
euc_jp/iso2022_jp_2: all 280 now round-trip;npm testpasses (178).