# paulmillr/es6-shim

ECMAScript 6 compatibility shims for legacy JS engines

Repository: https://github.com/paulmillr/es6-shim
Canonical: https://ross.abutalabs.com/products/es6-shim
Homepage: http://paulmillr.com
Language: JavaScript
License: MIT
License Family: permissive
Topics: ecmascript, ecmascript6, es6, shim
Last push: 2026-04-16T04:37:38+00:00

## Health v2 (maintenance only)
Score: 57/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 77, release rhythm 8, longevity 100
- inputs: {"age_days": 5366, "days_push": 139, "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 3098, forks 373 (observed 2026-08-28T04:07:43.441222+00:00)

## What it is
A JavaScript library providing ECMAScript 6 (Harmony) compatibility shims for legacy JS engines, polyfilling features like Map, Set, Promise, and new String/RegExp methods. It lets code written against ES6 run in older browsers and Node.js environments.

## Use cases
- run ES6 code in legacy browsers
- polyfill Promise Map and Set in old engines
- support String.prototype.startsWith and endsWith in IE
- make old Node.js versions behave like ES6
- add ES6 methods to legacy JavaScript runtime

## When to choose
- you must support legacy browsers or JS engines lacking ES6 features
- you need spec-compliant polyfills for Map, Set, Promise, and string methods

## When to avoid
- your target environments already support ES6 natively
- you only need one or two features - standalone per-method shims are lighter
- you want modern transpilation via Babel instead of runtime shims

## Facets
- artifact type: library
- maturity: maintenance
- function: developer-tools
- domain: web-development, developer-tools, programming-languages
- platform: browser, cross-platform
- tags: es6, shim, polyfill, ecmascript, javascript, compatibility, nodejs

## Member repositories
- paulmillr/es6-shim (main) score 57

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:43.441222+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 2026-08-29T18:46:22.393072+00:00, confidence not recorded.
  - readme: https://github.com/paulmillr/es6-shim (fetched 2026-08-28T04:07:43.441222+00:00, sha c9a14499b736)
  - homepage: http://paulmillr.com (fetched 2026-08-29T09:42:36.396942+00:00, sha 65a1cbcce56d)
  - registry_npm: https://registry.npmjs.org/es6-shim (fetched 2026-08-29T09:42:36.399369+00:00, sha ef93a06a1238)
- Data as of 2026-08-30T08:39:29.467469+00:00.