dejapanify

Auto-converts Japanese form fields between half-width and full-width (半角・全角) so forms stop rejecting correct input.

Japanese web forms enforce a character-width convention that has no equivalent in other languages. The same character exists in two Unicode forms — half-width (半角) "1500001" and full-width (全角) "１５００００１" — and a given field usually accepts exactly one of them. Which one is rarely marked on the input itself. It's printed in Japanese beside the field (「半角数字で入力してください」) or hidden in a pattern attribute. Meanwhile your IME produces whichever form its current mode happens to emit. So you type a phone number that looks correct, submit, and get a validation error you cannot visually distinguish from what you typed. Then you retype it by hand. dejapanify reads what each field actually asks for and converts your text to match. フリガナ やまだ たろう → ヤマダ　タロウ 郵便番号 １５０－０００１ → 1500001 メール ｅｘａｍｐｌｅ＠… → example@… It also follows the form's own format: 携帯電話 (例：090-1234-5678) ０９０１２３４５６７８ → 090-1234-5678 希望年収 (例：5,000,000) ６００００００ → 6,000,000 ローマ字（大文字） yamada taro → YAMADA TARO Hyphens and commas are added or removed to match the page's example or instruction. Landline numbers are split correctly using the official Japanese area-code table. SPLIT BOXES AND FORM ERRORS • Paste 山田 太郎 into a 姓 box, or 090-1234-5678 into the first of three phone boxes, and every box is filled. A full phone box moves you on. • When a form rejects you with only 「入力内容に誤りがあります」, a small panel names the fields at fault and jumps to the first. • Pressing 確認画面へ with a required field empty stops that one press and shows which field. Press again to go on anyway. • Optional, off by default: if a site empties the whole form when it rejects it, offer to refill it from a copy kept in that tab for up to 30 minutes. HOW IT DECIDES It does not guess. It collects signals and converts only when they are conclusive: • pattern attributes — what the site actually enforces • the printed instruction — 「半角数字で入力してください」 • the page's own example — 例：090-1234-5678 • autocomplete — postal-code, tel, email • type and inputmode • field names and labels — name_kana, 「フリガナ」 A field labelled 「フリガナ」 converts on its own, because that is unambiguous. A field labelled only 「住所」 is left alone, because rewriting an address on a hunch is worse than doing nothing. WHAT IT WILL NEVER DO • Convert password, hidden, file, date or checkbox inputs • Read or change payment card fields or bank account numbers • Convert a field it could not identify • Convert meaning — 山田 never becomes ヤマダ; only width changes, plus letter case and separators when the form asks for them • Change letter case where the page says case matters (大文字・小文字を区別) • Act while your IME is mid-composition • Send anything anywhere HOW IT WORKS Conversion runs when you leave a field, and again as a sweep when you submit, which catches autofilled values you never focused. After each conversion a small notice shows what changed, with a one-click undo. Ctrl+Z also works. Everything is configurable: turn off individual conversion types, adjust how confident it must be before acting, or disable it per site. PRIVACY No data collection. No network requests. No account. The extension contains no fetch, no XHR and no remote scripts — every conversion happens locally in your browser. The optional form refill keeps its copy in that tab's session storage and deletes it within 30 minutes. Open source (MIT): https://github.com/b1gmaw/dejapanify