zen-json-patch

A monstrously fast TypeScript library for generating JSON Patch (RFC 6902) diffs between two JSON objects.

Goal

The primary goal is to provide significantly faster diff generation compared to existing libraries, especially for large or complex objects.

Installation

npm install zen-json-patch
# or
yarn add zen-json-patch
# or
pnpm add zen-json-patch

Basic Usage

import { diff } from 'zen-json-patch';

const obj1 = { a: 1, b: "hello" };
const obj2 = { a: 2, c: "world" };

const operations = diff(obj1, obj2);

console.log(operations);
// Expected output (order might vary slightly depending on internal details):
// [
//   { op: 'remove', path: '/b' },
//   { op: 'replace', path: '/a', value: 2 },
//   { op: 'add', path: '/c', value: 'world' }
// ]

Current Status & Limitations

• Array Diffing: Currently uses a naive element-wise comparison for arrays. This is correct but potentially less performant than optimized algorithms (like Myers diff) for certain array changes (e.g., large insertions/deletions near the beginning, element moves). A performant array diff implementation is planned for a future release.
• Operations Generated: Primarily generates add, remove, and replace operations. move and copy operations are not currently generated as optimizations.

Development

• Testing: npm test
• Benchmarking: npm run bench (requires dev dependencies)
• Building: npm run build

License

MIT (To be added)