react / react/react-native

[iOS] The styling does not change when the CJK character enter TextInput

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Component: TextInput Issue: Author Provided Repro Needs: Triage :mag: Newer Patch Available Platform: iOS
Dominant language
C++
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Forks
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Avg merge
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Merged PRs (30d)
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Description

Description

When entering CJK characters in the TextInput component, the styling does not change.

I wanted to change the styling according to the type of characters entered, but I don't think react can detect the state change.

The example screen is,
The even number of letters is red
The odd-numbered letter is a simple logic that handles it in blue.

Logic does not work in Korean while it works normally in the English environment.
From searching, it seems that this phenomenon occurs in Korean, Chinese, and Japanese equally.

Video & Code

Steps to reproduce
  1. The even number of letters color is red, The odd-numbered letter color is blue.
  2. type english / type CJK Character
React Native Version

0.72.6

Affected Platforms

Runtime - iOS

Output of npx react-native info
System:
  OS: macOS 13.5
  CPU: (10) arm64 Apple M1 Pro
  Memory: 66.83 MB / 16.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 16.14.0
    path: ~/.nvm/versions/node/v16.14.0/bin/node
  Yarn:
    version: 1.22.19
    path: ~/.nvm/versions/node/v16.14.0/bin/yarn
  npm:
    version: 8.3.1
    path: ~/.nvm/versions/node/v16.14.0/bin/npm
  Watchman:
    version: 2023.10.23.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.14.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 22.4
      - iOS 16.4
      - macOS 13.3
      - tvOS 16.4
      - watchOS 9.4
  Android SDK:
    API Levels:
      - "28"
      - "29"
      - "30"
      - "31"
      - "33"
      - "34"
    Build Tools:
      - 29.0.2
      - 29.0.3
      - 30.0.2
      - 30.0.3
      - 31.0.0
      - 32.0.0
      - 33.0.0
    System Images:
      - android-29 | Intel x86 Atom_64
      - android-29 | Google APIs ARM 64 v8a
      - android-29 | Google APIs Intel x86 Atom_64
      - android-30 | Google APIs Intel x86 Atom
      - android-30 | Google Play Intel x86 Atom
      - android-33 | Google APIs ARM 64 v8a
    Android NDK: Not Found
IDEs:
  Android Studio: 2021.3 AI-213.7172.25.2113.9014738
  Xcode:
    version: 14.3.1/14E300c
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 11.0.17
    path: /usr/bin/javac
  Ruby:
    version: 3.1.4
    path: /Users/dev002/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.2.0
    wanted: 18.2.0
  react-native:
    installed: 0.72.6
    wanted: 0.72.6
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: false
iOS:
  hermesEnabled: true
  newArchEnabled: false
Stacktrace or Logs
-
Reproducer

https://github.com/1nno-vator/rn-textinput-cjk-issue

Screenshots and Videos

Work Well: Type English
Simulator Screenshot - iPhone 13 - 2023-12-14 at 16 00 20

[Video] Work Well: Type English
https://github.com/facebook/react-native/assets/55885561/d3f59132-27d0-4e15-b0ed-59eb0f89affc

Error Case: Type Korean
Simulator Screenshot - iPhone 13 - 2023-12-14 at 16 00 30

[Video] Error Case: Type Korean
https://github.com/facebook/react-native/assets/55885561/b86e14bd-bd9f-49eb-a42f-a347e48dc779

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked rn-textinput-cjk-issue reproducer and compare TextInput behavior when entering English versus Korean, Chinese, or Japanese on iOS. Trace how TextInput changes are propagated to the styling logic, then verify that the even/odd character styling updates during CJK input without regressing English input.

Written by the indexing model from the issue text.

Assessment

Tech stack
ios, react-native
Domain
mobile
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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