# rtfeldman/seamless-immutable

Immutable data structures for JavaScript which are backwards-compatible with normal JS Arrays and Objects.

Repository: https://github.com/rtfeldman/seamless-immutable
Canonical: https://ross.abutalabs.com/products/seamless-immutable
Language: JavaScript
License: BSD-3-Clause
License Family: permissive
Archived: true
Last push: 2021-06-25T16:12:52+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 4331, "days_push": 1895, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 5329, forks 197 (observed 2026-08-28T04:09:15.690549+00:00)

## What it is
A JavaScript library providing immutable data structures that are backwards-compatible with normal Arrays and Objects. It wraps vanilla JS data in frozen, mutation-resistant variants usable anywhere standard objects and arrays are expected.

## Use cases
- make javascript objects immutable
- prevent accidental mutation of arrays and objects
- immutable state for react components
- deep freeze nested data structures
- use immutable data with vanilla js apis
- faster deep cloning of large nested objects

## When to choose
- you want immutability without changing how you use arrays and objects
- you need compatibility with functions expecting vanilla JS data structures
- you want a lightweight alternative to heavier immutable libraries

## When to avoid
- you need persistent data structures with structural sharing APIs like Immutable.js
- you target browsers lacking ECMAScript 5 features
- you need actively developed library with ongoing updates

## Facets
- artifact type: library
- maturity: maintenance
- function: serialization, state-management
- domain: web-development, frontend, developer-tools
- platform: browser
- tags: immutable-data, object-freeze, backwards-compatible, react-state, nodejs, javascript

## Member repositories
- rtfeldman/seamless-immutable (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:15.690549+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 2026-08-29T17:58:53.838301+00:00, confidence not recorded.
  - readme: https://github.com/rtfeldman/seamless-immutable (fetched 2026-08-28T04:09:15.690549+00:00, sha f1209d99a553)
  - registry_npm: https://registry.npmjs.org/seamless-immutable (fetched 2026-08-29T08:53:47.402467+00:00, sha 05e10ff889fb)
- Data as of 2026-08-30T08:39:29.467469+00:00.