Fix useInput crash on unmapped keyName codes#902
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sindresorhus merged 2 commits intoMar 21, 2026
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parseKeypress used a non-null assertion (keyName[code]!) that returned undefined for escape sequences not in the keyName map (e.g. Ctrl+F1 sending ESC[1;5P). This undefined propagated to use-input.ts where .startsWith() was called on it, causing a TypeError crash. - Replace keyName[code]! with keyName[code] ?? '' to handle unmapped codes - Add defensive ?? '' guard in use-input.ts ctrl branch - Add missing vt220-style F1-F4 entries ([P]-[S]) to keyName map - Add unit tests for parseKeypress and integration tests for the fix Fixes vadimdemedes#901
- Use Unicode escapes (\u001B) instead of hex escapes (\x1b) - Capitalize comments to satisfy capitalized-comments rule
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Summary
TypeError: Cannot read properties of undefined (reading 'startsWith')crash inuseInputwhen the terminal sends escape sequences with Ctrl modifiers whose key codes aren't in thekeyNamemap (e.g. Ctrl+F1 viaESC[1;5P)keyName[code]!non-null assertion inparse-keypress.tsreturnedundefinedfor unmapped codes, which propagated touse-input.tsand crashed on.startsWith()[P]–[S]) to thekeyNamemap so these keys resolve correctlyFixes #901
Changes
src/parse-keypress.ts:keyName[code]!withkeyName[code] ?? ''— removes unsafe non-null assertion[P→f1,[Q→f2,[R→f3,[S→f4tokeyNamemapsrc/hooks/use-input.ts:?? ''guard onkeypress.namein thectrlbranchTests:
test/parse-keypress.tsunit tests verifying key identity and empty-string fallbackTest plan
npx tsc --noEmitpasseshooks-use-input,hooks-use-input-navigation,hooks-use-input-kitty,input-parser,parse-keypress)