human-readable-diff

A zero-dependency, lightweight Node.js utility to generate human-readable descriptions of object changes.

한국어 문서 (Korean Docs)

Why this?

• 🪶 Tiny: Zero runtime dependencies. No Lodash, No Moment.js.
• 🛡️ Robust: 100% TypeScript with strict types.
• ⚡ DX-First: Immediate usage with zero config.
• 🌍 i18n Support: Built-in support for English and Korean.

Installation

npm install human-readable-diff
# or
yarn add human-readable-diff
# or
pnpm add human-readable-diff

Usage

Basic Usage (Pure JS/TS)

import { getHumanDiff } from 'human-readable-diff';

const before = { price: 100, status: 'pending' };
const after = { price: 200, status: 'success' };

const diff = getHumanDiff(before, after);
console.log(diff);
// Output:
// [
//   "price changed from 100 to 200",
//   "status changed from 'pending' to 'success'"
// ]

With Nested Objects & Arrays

const before = {
  user: { name: 'Alice', tags: ['admin'] }
};
const after = {
  user: { name: 'Alice', tags: ['admin', 'super-user'] }
};

const diff = getHumanDiff(before, after);
console.log(diff);
// [ "user.tags added item 'super-user'" ]

Options: Exclude & Formatters

const diff = getHumanDiff(before, after, {
  exclude: ['id', 'updatedAt'],
  formatters: {
    price: (val) => `$${val.toFixed(2)}`
  }
});

NestJS Example

Easily integrate into your services for audit logs.

import { Injectable } from '@nestjs/common';
import { getHumanDiff } from 'human-readable-diff';

@Injectable()
export class AuditService {
  logChange(oldEntity: any, newEntity: any) {
    const changes = getHumanDiff(oldEntity, newEntity, {
      exclude: ['password', 'createdAt']
    });
    
    if (changes.length > 0) {
      console.log('Entity updated:', changes);
      // Save to database...
    }
  }
}

API

getHumanDiff(before, after, options?)

• before: Original object.
• after: New object.
• options:
  • exclude: Array of strings (dot notation supported) to ignore.
  • formatters: Object mapping keys to formatter functions.
  • lang: 'en' | 'ko' (default: 'en').

License

ISC