# tc39/proposal-nullish-coalescing

Nullish coalescing proposal x ?? y

Repository: https://github.com/tc39/proposal-nullish-coalescing
Canonical: https://ross.abutalabs.com/products/proposal-nullish-coalescing
Homepage: https://tc39.github.io/proposal-nullish-coalescing/
Language: HTML
License Family: other
Archived: true
Last push: 2023-01-28T20:48:22+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 3331, "days_push": 1313, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, archived, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1226, forks 21 (observed 2026-08-28T04:04:03.162554+00:00)

## What it is
The TC39 specification repository for the ECMAScript nullish coalescing operator (??), a Stage 4 language proposal that provides default values only when a value is null or undefined. It contains the proposal explainer, motivation, syntax examples, and the formal specification draft.

## Use cases
- understand how the ?? operator works in javascript
- learn difference between ?? and || for default values
- read the ecmascript spec for nullish coalescing
- find examples of nullish coalescing operator usage
- check status of the tc39 nullish coalescing proposal

## When to choose
- you need authoritative semantics of the ?? operator
- you want to understand why || mishandles falsy values like 0 or ''
- you're implementing a javascript engine or transpiler

## When to avoid
- you want a library or tool to install
- you need general javascript tutorials rather than language specification
- you're looking for optional chaining documentation specifically

## Facets
- artifact type: learning-resource
- maturity: maintenance
- function: programming-language, documentation
- domain: programming-languages, web-development
- platform: browser, cross-platform
- tags: ecmascript, tc39, language-proposal, specification, nullish-coalescing, javascript-operator, javascript, specifications, nodejs

## Member repositories
- tc39/proposal-nullish-coalescing (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:03.162554+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 2026-08-30T06:15:21.238652+00:00, confidence not recorded.
  - readme: https://github.com/tc39/proposal-nullish-coalescing (fetched 2026-08-28T04:04:03.162554+00:00, sha eaca18eb8889)
  - homepage: https://tc39.github.io/proposal-nullish-coalescing/ (fetched 2026-08-29T12:23:11.907415+00:00, sha b69f8652c698)
- Data as of 2026-08-30T08:39:29.467469+00:00.