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microsoft/reflect-metadata

Prototype for a Metadata Reflection API for ECMAScript observed · 2026-08-28

github.com/microsoft/reflect-metadata · homepage · TypeScript · Apache-2.0 (permissive) observed · 2026-08-28

Health v2 · maintenance only

67/100

  • Activity 99
  • Release rhythm 8
  • Longevity 100
How is this computed?

round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10) — computed 2026-09-03. Adoption (stars, forks) is never an input.

  • gap_med: n/a
  • age_days: 4193
  • days_rel: n/a
  • days_push: 9
  • n_releases_24m: 0

Full methodology

Adoption not part of the score

3359 stars · 191 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

A polyfill implementing the proposed ECMAScript Metadata Reflection API, adding metadata methods to the global Reflect object for use with TypeScript's legacy experimental decorators. It is now in maintenance mode since the proposal is no longer being standardized, but remains supported for legacy decorator projects.

Use cases

  • add metadata to classes for dependency injection
  • runtime type assertions with decorators
  • build composable metadata-producing decorators
  • support legacy TypeScript experimentalDecorators projects
  • reflection and mirroring of class metadata in JavaScript

When to choose

  • your project uses TypeScript legacy --experimentalDecorators and needs Reflect.metadata
  • you maintain a DI framework or ORM that relies on decorator metadata
  • you need a consistent metadata API across libraries on older runtimes

When to avoid

  • you are starting a new project with standard Stage 3 decorators and decorator metadata
  • you need a standardized, future-proof metadata solution
  • your runtime already supports native decorator metadata

Facets

library · maturity maintenance

middleware developer-tools plugin-system developer-tools web-development programming-languages browser cross-platform reflection metadata decorators polyfill dependency-injection tc39-proposal nodejs javascript typescript

1 source

Member repositories

RepositoryRoleHealth v2
microsoft/reflect-metadatamain67

For agents

markdown · JSON · MCP: product_card(name="microsoft/reflect-metadata")

Data as of 2026-08-30T08:39:29.467469+00:00 · Report a problem