Unicode Properties are not supported/broken for Regular Expressions (Regex)

Description

The Unicode Properties feature for regular expression is supported for Node, Swift and Java (see References bellow). However, when I use that feature in my code, it returns a wrong answer (specifically I used \p{L} and the test method). For example, /\p{L}/u.test('a') returns false.

References

JS - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Unicode_Property_Escapes Swift - https://developer.apple.com/documentation/foundation/nsregularexpression Java - https://docs.oracle.com/javase/tutorial/essential/regex/unicode.html

React Native version:

System:
    OS: Windows 10 10.0.19041
    CPU: (4) x64 Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz
    Memory: 3.49 GB / 15.90 GB
  Binaries:
    Node: 14.5.0 - C:\Program Files\nodejs\node.EXE     
    Yarn: Not Found
    npm: 6.14.6 - C:\Program Files\nodejs\npm.CMD
    Watchman: Not Found
  SDKs:
    Android SDK:
      API Levels: 28, 29
      Build Tools: 28.0.3, 29.0.2, 29.0.3, 30.0.1
      System Images: android-29 | Google APIs Intel x86 Atom, android-29 | Google Play Intel x86 Atom
      Android NDK: Not Found
  IDEs:
    Android Studio: Version  4.0.0.0 AI-193.6911.18.40.6626763
  Languages:
    Java: 1.8.0_211
    Python: 2.7.18
  npmPackages:
    @react-native-community/cli: Not Found
    react: 16.13.1 => 16.13.1
    react-native: 0.63.2 => 0.63.2
  npmGlobalPackages:
    *react-native*: Not Found

Steps To Reproduce

Provide a detailed list of steps that reproduce the issue.

1. run the code

console.log(/\p{L}/u.test('a'));
console.log(/\p{L}/u.test('ש'));

anywhere in your app component.

Expected Results

/\p{L}/u.test('a') and /\p{L}/u.test('ש') should return true (they have the unicode property “Letter”). they both return false.

Snack, code example, screenshot, or link to a repository:

import React from 'react';
import { View, Text } from 'react-native';

function App() {
  console.log(/\p{L}/u.test('a'));
  console.log(/\p{L}/u.test('ש'));
  return (
    <View>
      <Text>App</Text>
    </View>
  );
}

export default App;

[conradlo]

I had the same issue recently. Out team’s solution is to use the @babel/plugin-proposal-unicode-property-regex plugin to transpile the unicode regex.

[arnaudambro]

I had the same issue recently. Out team’s solution is to use the @babel/plugin-proposal-unicode-property-regex plugin to transpile the unicode regex.

it doesn’t do anything for me, is there an extra step to do ?

[EDIT]

I forgot to update my babel config in babel.config.js

module.exports = {
  presets: ['module:metro-react-native-babel-preset'],
  plugins: ['@babel/plugin-proposal-unicode-property-regex'],
};