# facebook/regenerator

Source transformer enabling ECMAScript 6 generator functions in JavaScript-of-today.

Repository: https://github.com/facebook/regenerator
Canonical: https://ross.abutalabs.com/products/regenerator
Homepage: http://facebook.github.io/regenerator/
Language: JavaScript
License: MIT
License Family: permissive
Archived: true
Last push: 2024-02-29T11:04:34+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": 4715, "days_push": 916, "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 3824, forks 1130 (observed 2026-08-28T04:08:22.079456+00:00)

## What it is
Regenerator is a source transformer that compiles ECMAScript 2015 generator functions (yield) and async iteration syntax down to efficient ES5 JavaScript. It is available as a CLI, a programmatic API, and an AST transformation, with a small runtime library.

## Use cases
- transpile ES6 generator functions to ES5 for older browsers
- use yield-based async code in environments without native generator support
- transform generator syntax programmatically on a JavaScript AST
- downlevel async iteration and for-await loops to ES5
- run generator-based code in legacy Node.js versions

## When to choose
- you must support ES5-only environments (old browsers, legacy Node) while writing generator/async-iteration syntax
- you need a standalone, focused generator-to-ES5 transform rather than a full transpiler
- you want to manipulate or transform generator syntax at the AST level

## When to avoid
- your targets already support ES2015 generators natively (modern browsers and Node)
- you need broad ES6+ transpilation - use Babel, which embeds regenerator for this purpose
- the project is in maintenance mode with minimal new development

## Facets
- artifact type: library
- maturity: maintenance
- function: compiler, parser, developer-tools
- domain: web-development, compilers, programming-languages, developer-tools
- platform: cross-platform
- tags: transpiler, es6, generators, yield, source-transformation, es5, desugaring, babel, nodejs, javascript

## Member repositories
- facebook/regenerator (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:22.079456+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 2026-08-29T18:26:22.983633+00:00, confidence not recorded.
  - readme: https://github.com/facebook/regenerator (fetched 2026-08-28T04:08:22.079456+00:00, sha 3156dba63038)
  - homepage: http://facebook.github.io/regenerator/ (fetched 2026-08-29T09:21:16.420933+00:00, sha 39e33f0fd81a)
  - registry_npm: https://registry.npmjs.org/regenerator (fetched 2026-08-29T09:21:16.429745+00:00, sha e865e17a3c26)
- Data as of 2026-08-30T08:39:29.467469+00:00.