expo-gbk-converter

An Expo native module to decode GBK/GB18030 encoded text from base64 strings. This is particularly useful for parsing Chinese encoded files (like CSV exports from Alipay, WeChat, etc.) in React Native/Expo applications.

Installation

npx expo install expo-gbk-converter

Or using npm/yarn:

npm install expo-gbk-converter
# or
yarn add expo-gbk-converter

Requirements

• Expo SDK 51+
• iOS 15.1+
• Android minSdkVersion 24+

Usage

import { decodeGBK } from 'expo-gbk-converter';
import * as FileSystem from 'expo-file-system';

// Read a GBK encoded file as base64
const base64Content = await FileSystem.readAsStringAsync(fileUri, {
  encoding: FileSystem.EncodingType.Base64,
});

// Decode GBK to UTF-8 string
const utf8Text = await decodeGBK(base64Content);

console.log(utf8Text); // Now you have the readable Chinese text

API

decodeGBK(base64: string): Promise<string>

Decodes a GBK/GB18030 encoded base64 string to UTF-8 text.

Parameters:

• base64 (string): Base64 encoded string of GBK/GB18030 data

Returns:

• Promise<string>: Decoded UTF-8 text

Throws:

• Error if the base64 string is invalid
• Error if the data cannot be decoded as GBK/GB18030

Platform Support

| Platform | Support | | -------- | ------- | | iOS | ✅ | | Android | ✅ | | Web | ❌ |

Note: Web platform is not supported because browsers don't have native GBK decoding support. Consider using a JavaScript-based decoder like iconv-lite for web.

Use Cases

• Parsing Alipay (支付宝) bill exports
• Reading legacy Chinese encoded files
• Processing CSV files with GBK encoding

Example: Parsing Alipay Bills

import { decodeGBK } from 'expo-gbk-converter';
import * as FileSystem from 'expo-file-system';
import Papa from 'papaparse';

async function parseAlipayBill(fileUri: string) {
  // Read file as base64
  const base64 = await FileSystem.readAsStringAsync(fileUri, {
    encoding: FileSystem.EncodingType.Base64,
  });

  // Decode GBK to UTF-8
  const csvText = await decodeGBK(base64);

  // Normalize line endings
  const normalizedText = csvText.replace(/\r\n/g, '\n').replace(/\r/g, '\n');

  // Parse CSV
  const result = Papa.parse(normalizedText, {
    skipEmptyLines: true,
  });

  return result.data;
}

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Author

Evan Sun [email protected]

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