# FormidableLabs/react-fast-compare

fastest deep equal comparison for React

Repository: https://github.com/FormidableLabs/react-fast-compare
Canonical: https://ross.abutalabs.com/products/react-fast-compare
Language: JavaScript
License: MIT
License Family: permissive
Last push: 2024-03-20T20:11:52+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 3067, "days_push": 896, "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 1666, forks 54 (observed 2026-08-28T04:05:19.095876+00:00)

## What it is
A tiny, fast deep-equality comparison library for JavaScript, forked from fast-deep-equal with extra handling for React-specific circular references like elements. It is designed primarily for use with React.memo and shouldComponentUpdate to prevent unnecessary re-renders.

## Use cases
- deeply compare props in React.memo to avoid re-renders
- implement shouldComponentUpdate with deep equality checks
- compare nested objects and arrays for equality in JavaScript
- check equality of Date and RegExp objects
- compare values containing React elements without circular reference errors

## When to choose
- you need deep equality checks in React.memo or shouldComponentUpdate after profiling confirms re-renders are a bottleneck
- you need a very small (<660 bytes) and fast general-purpose deep-equal function
- your data includes React elements or other circular references

## When to avoid
- shallow comparison via default React.memo or PureComponent would suffice
- your objects contain circular references outside React elements
- you need equality checks for Maps, Sets, or other special structures not mentioned as supported

## Facets
- artifact type: library
- maturity: maintenance
- function: serialization
- domain: frontend, web-development, developer-tools
- platform: browser, cross-platform
- tags: deep-equality, react, performance-optimization, react-memo, should-component-update, nodejs

## Member repositories
- FormidableLabs/react-fast-compare (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:19.095876+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 2026-08-30T03:42:56.728319+00:00, confidence not recorded.
  - readme: https://github.com/FormidableLabs/react-fast-compare (fetched 2026-08-28T04:05:19.095876+00:00, sha 6c9a8be42307)
  - registry_npm: https://registry.npmjs.org/react-fast-compare (fetched 2026-08-29T11:16:37.820478+00:00, sha ef3eeb1403b8)
- Data as of 2026-08-30T08:39:29.467469+00:00.