use-json

A TypeScript library that extends JavaScript's native JSON functionality to support serialization of Maps, Sets, and RegExp objects.

Why This Package?

JavaScript's built-in JSON.stringify() and JSON.parse() functions don't support serializing certain built-in objects like Map, Set, and RegExp. When you try to serialize these objects:

// Standard JSON
JSON.stringify(new Map([['key', 'value']])); // '{}'
JSON.stringify(new Set([1, 2, 3])); // '{}'
JSON.stringify(/test/gi); // '{}'

This library solves this limitation by providing an enhanced JSON serializer that properly handles these data types while maintaining compatibility with the standard JSON format.

🚀 Features

• ✅ Full support for Map, Set, and RegExp serialization
• 🔄 Maintains the original JSON API's simplicity
• 📦 Type-safe with TypeScript
• 🎯 Compatible with custom replacer and reviver functions
• 🔍 Preserves all object properties (like RegExp flags)
• 🎭 Handles nested structures seamlessly

📦 Installation

npm install use-json
# or
yarn add use-json

🛠️ Usage

Basic Usage

import JSON from 'use-json';

// Maps
const map = new Map([['key', 'value']]);
const mapJson = JSON.stringify(map);
const mapBack = JSON.parse(mapJson);
// mapBack instanceof Map === true

// Sets
const set = new Set([1, 2, 3]);
const setJson = JSON.stringify(set);
const setBack = JSON.parse(setJson);
// setBack instanceof Set === true

// RegExp
const regexp = /test/gi;
const regexpJson = JSON.stringify(regexp);
const regexpBack = JSON.parse(regexpJson);
// regexpBack instanceof RegExp === true

Nested Structures

const complex = {
	map: new Map([['key', new Set([1, 2, 3])]]),
	set: new Set([new Map([['nested', 'value']])]),
	regexp: /test/gi
};

const json = JSON.stringify(complex);
const restored = JSON.parse(json);
// All nested structures are properly restored

Custom Replacer and Reviver

// Custom replacer
const json = JSON.stringify(data, (key, value) => {
	if (key === 'sensitive') return undefined;
	return value;
});

// Custom reviver
const obj = JSON.parse(json, (key, value) => {
	if (key === 'date') return new Date(value);
	return value;
});

🧪 Testing

# Run tests
yarn test

📝 How It Works

The library works by:

1. Adding type identifiers to serialized objects (__map__, __set__, __regexp__)
2. Converting Maps and Sets to arrays during serialization
3. Preserving RegExp flags and source
4. Automatically reconstructing the original objects during parsing

📄 License

MIT

👨‍💻 Contributing

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

👨‍💻 Author

Felipe Rohde

• Twitter: @felipe_rohde
• Github: @feliperohdee
• Email: [email protected]