@toolsycc/json-diff

A small but powerful utility to compare, intersect, or subtract JSON objects deeply.
✅ Works seamlessly with both TypeScript and JavaScript (ESM & CommonJS).

Features

• Detects:
  • Added keys
  • Removed keys
  • Changed values
  • Identical key-values (intersection)
  • Keys to subtract from another JSON
• Fully recursive (works with nested structures)
• Useful for state comparison, config patching, debugging
• Lightweight, no dependencies

Install

pnpm add @toolsycc/json-diff

Or with npm:

npm install @toolsycc/json-diff

Example usage

🟦 TypeScript

import { diffJson, intersectJson, subtractJson } from '@toolsycc/json-diff';

const a = { name: 'Seb', age: 42, extra: true };
const b = { name: 'Seb', age: 33 };

console.log(diffJson(a, b));
// → { added: {}, removed: { extra: true }, changed: { age: [42, 33] } }

console.log(intersectJson(a, b));
// → { name: 'Seb' }

console.log(subtractJson(a, b));
// → { age: 42, extra: true }

🟨 JavaScript (CommonJS)

const { diffJson, intersectJson, subtractJson } = require('@toolsycc/json-diff');

console.log(diffJson({ a: 1 }, { a: 2 }));

🟩 JavaScript (ESM)

import { diffJson } from '@toolsycc/json-diff';

console.log(diffJson({ a: 1 }, { a: 2 }));

Functions

| Function | Description | |-------------------|-------------| | diffJson(a, b) | Returns { added, removed, changed } | | intersectJson(a, b) | Returns only the shared key-values | | subtractJson(a, b) | Removes values from a that also exist in b |

Examples

| A | B | diffJson(A, B) | |--------------------------------|-------------------------------|------------------------------------------| | {name: 'Seb', age: 42} | {name: 'Seb', age: 33} | changed: { age: [42, 33] } | | {user: {role: 'admin'}} | {user: {role: 'user'}} | changed: { user: [...] } | | {a: 1, b: 2} | {a: 1, c: 3} | removed: { b: 2 }, added: { c: 3 } |

Live demonstration

Try it: Toolsy

Motivation

This utility was built to help developers quickly understand differences between JSON structures.
Whether debugging frontend state, comparing API responses, or writing patches — it's designed to give you clean, actionable data.

Author

Made by @Sebog33
Follow Toolsy for more tiny dev-focused utilities.

License

MIT