@batoanng/utils

A collection of general-purpose utility functions and React hooks used across multiple packages and applications.

✨ Features

• ✅ Typed utility functions (e.g. sleep, slugify, short ID generator)
• ⚙️ Server + client-safe helpers
• 🚦 In-memory rate limiter classes
• 🪝 React hooks like usePrevious and useIsomorphicLayoutEffect
• 🧪 Unit tested with Jest
• 📦 Lightweight and tree-shakable

📦 Installation

npm install @batoanng/utils

🚀 Usage

import { sleep, generateShortId } from '@batoanng/utils';

import { usePrevious } from '@batoanng/utils';

Rate limiting

import { FixedWindowRateLimiter, LeakyBucketRateLimiter, SlidingWindowRateLimiter } from '@batoanng/utils';

const apiLimiter = new LeakyBucketRateLimiter({
  capacity: 100,
  leakRatePerSecond: 50,
});

const loginLimiter = new FixedWindowRateLimiter({
  limit: 20,
  windowMs: 24 * 60 * 60 * 1000,
});

const withdrawalLimiter = new SlidingWindowRateLimiter({
  limit: 5,
  windowMs: 24 * 60 * 60 * 1000,
});

const result = apiLimiter.check('client-id');

if (!result.allowed) {
  console.log(`Retry after ${result.retryAfterMs}ms`);
}

Choose the limiter based on the traffic shape:

• LeakyBucketRateLimiter: smooths bursty traffic into a steady drain rate.
• FixedWindowRateLimiter: enforces simple limits per fixed interval, such as requests per day.
• SlidingWindowRateLimiter: enforces an exact moving-window limit when boundary accuracy matters.

All limiter classes expose the same methods:

• check(key?)
• getSnapshot(key?)
• reset(key?)
• clear()
• getTrackedKeyCount()

key defaults to "default" for single-resource limits. Pass a user, client, or resource ID to track limits independently.

📁 Included Utilities

src/
├── generateShortId.ts              # Short random string generator
├── getNormalisedError.ts           # Transforms mixed errors to unified format
├── rateLimit.ts                    # In-memory rate limiter classes
├── SearchSpecBuilder.ts            # Siebel-like query builder for filters
├── sleep.ts                        # Delay function using Promise
├── toSlug.ts                       # Converts string to URL-friendly slug
├── useIsomorphicLayoutEffect.tsx  # SSR-safe useLayoutEffect
├── usePrevious.tsx                # React hook to get previous value

🧹 Linting

This package uses the shared flat ESLint setup via eslint.config.mjs:

import base from '@batoanng/eslint-config/base';
import test from '@batoanng/eslint-config/test';

export default [...base, ...test];