# kentcdodds/use-deep-compare-effect

🐋 It's react's useEffect hook, except using deep comparison on the inputs, not reference equality

Repository: https://github.com/kentcdodds/use-deep-compare-effect
Canonical: https://ross.abutalabs.com/products/use-deep-compare-effect
Homepage: https://npm.im/use-deep-compare-effect
Language: TypeScript
License: MIT
License Family: permissive
Last push: 2024-08-21T08:09:36+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 2736, "days_push": 742, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1916, forks 88 (observed 2026-08-28T04:05:53.813763+00:00)

## What it is
A small React hook library that provides a drop-in replacement for useEffect which compares dependencies with deep equality instead of reference equality. It prevents effect callbacks from re-running when object or array dependencies are recreated each render without meaningful changes.

## Use cases
- run an effect only when object dependencies actually change in react
- avoid useEffect firing every render because a dependency object is recreated
- deep compare arrays in react hook dependencies
- replace useEffect with deep equality check for query variables
- stop unnecessary http requests triggered by reference-equal props

## When to choose
- your useEffect dependencies are objects or arrays that are new on every render
- you cannot restructure props or memoize dependencies to use plain useEffect
- you want a tiny, focused drop-in hook with no extra dependencies

## When to avoid
- your dependencies are primitives like numbers, strings, or booleans
- you can solve the problem with useMemo, useCallback, or better data flow
- your dependency objects contain functions defined during render, which still trigger every render

## Facets
- artifact type: library
- maturity: maintenance
- function: state-management, developer-tools
- domain: frontend, web-development, developer-tools
- platform: browser
- tags: react-hooks, useeffect, deep-comparison, react, nodejs, web-server

## Member repositories
- kentcdodds/use-deep-compare-effect (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:53.813763+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:10:17.959096+00:00, confidence not recorded.
  - readme: https://github.com/kentcdodds/use-deep-compare-effect (fetched 2026-08-28T04:05:53.813763+00:00, sha 1a0606ca4f5b)
  - registry_npm: https://registry.npmjs.org/use-deep-compare-effect (fetched 2026-08-29T10:49:47.719339+00:00, sha 94b39b9da90e)
- Data as of 2026-08-30T08:39:29.467469+00:00.