react-native-codepad

A native code editor for React Native. It runs its own engine in Kotlin on Android and Swift on iOS, with tree-sitter highlighting and no WebView.

What I built

Built on Nitro Modules and published as 16 npm packages: the core and one per language.
One set of test vectors that both the Kotlin and Swift engines run.
Each engine also has about 30 test files of its own.
IME replay fixtures cover Gboard paste, CJK input and emoji backspace on Android, and kana, pinyin and autocorrect on iOS.
Find and replace with literal or regex queries, hardware keyboard support, a toolbar API, three themes, auto indent and auto-closing brackets.
The editor follows the keyboard animation frame by frame.