react-deep-check

Lightweight deep equality helpers and React hooks for stable dependency management and optimization.

Features

- deepEqual(a,b) fast structural comparison (supports cycles, Map, Set, Date, RegExp, typed arrays)
- stableHash(value) deterministic structural hash (order-independent for Set, sorted object keys)
- Hooks:
- useDeepCompareEffect(effect, deps) like useEffect but deep-compares deps
- useDeepCompareMemoize(value) returns stable ref that only changes when deep-equal changes
- useShallowStable(obj) preserves reference for shallow-equal objects across renders
- useStableHash(value) deep structural hash memoized hook

Install

``bash
npm install react-deep-check


or


yarn add react-deep-check
`

Peer dependency: react >=16.8.

Usage

`tsx
import { useDeepCompareEffect, deepEqual, useStableHash } from 'react-deep-check';

function Demo({ config }) {
const hash = useStableHash(config);
useDeepCompareEffect(() => {
// runs only when config structurally changes
console.log('config changed');
}, [config]);
return

;
}
`

API

$3

Options:
- strict (default true) – same semantics as === except NaN equals NaN.
- compare(a,b,path) custom comparator may return boolean to override or undefined to continue default.

$3

Generates a stable base36-ish style string representing value structure (not cryptographic).

$3

Drop-in replacement for useEffect` when your deps are objects/arrays built inline.

$3

Returns memoized value reference only updating when deep-equal differs.

$3

Keeps same reference for objects whose shallow key/value pairs are unchanged.

$3

Returns memoized structural hash string for a value.

Why not JSON.stringify?

- Key order differences produce false negatives.
- Fails on cycles, Set, Map, functions, RegExp.
- Performance overhead due to full serialization each render.

Performance Notes

- Avoids allocations where possible; early exit on inequality.
- Set equality uses O(n^2) fallback; acceptable for typical small sizes. Future optimization: bucket hashing.

License

MIT