@philiprehberger/memo-map

Memoization with WeakMap support for object keys, LRU eviction, and TTL.

Installation

npm install @philiprehberger/memo-map

Usage

import { memoize } from '@philiprehberger/memo-map';

// Basic memoization
const expensive = memoize((n: number) => {
  console.log('computing...');
  return n * n;
});

expensive(5); // computing... => 25
expensive(5); // => 25 (cached)

// With LRU eviction and TTL
const cached = memoize(fetchUser, {
  maxSize: 100,
  ttl: 60_000, // 1 minute
});

// Object args use WeakMap automatically
const getSize = memoize((obj: object) => Object.keys(obj).length);

// Custom key function
const byId = memoize(
  (user: { id: number; name: string }) => user.name.toUpperCase(),
  { key: (user) => user.id },
);

API

memoize<T>(fn, options?)

Wraps fn with memoization. Returns the memoized function with additional properties.

Options:

| Option | Type | Description | |--------|------|-------------| | maxSize | number | Maximum cache entries (LRU eviction) | | ttl | number | Time-to-live in milliseconds | | key | (...args) => unknown | Custom cache key function |

Returned function extras:

• .cache — The underlying Map instance
• .clear() — Clear all cached entries

Key resolution (default):

• Single primitive arg: used directly as key
• Single object arg: stored in a WeakMap
• Multiple args: JSON.stringify(args)

Development

npm install
npm run build
npm test

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License

MIT