# josh/css-explain

SQL EXPLAIN for CSS selectors

Repository: https://github.com/josh/css-explain
Canonical: https://ross.abutalabs.com/products/css-explain
Homepage: http://josh.github.io/css-explain/
Language: JavaScript
License: MIT
License Family: permissive
Archived: true
Last push: 2015-07-25T19:10:44+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": 5249, "days_push": 4057, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1068, forks 40 (observed 2026-08-28T04:03:27.429730+00:00)

## What it is
A JavaScript library that analyzes CSS selectors the way SQL EXPLAIN analyzes queries, computing specificity, category, and an efficiency score. It models WebKit's rule-set indexing optimizations to explain selector performance.

## Use cases
- analyze css selector performance
- compute css selector specificity
- explain why a css selector is slow
- audit stylesheets for inefficient selectors
- learn how browsers index css rules

## When to choose
- you want to score or debug CSS selector efficiency in JavaScript
- you need programmatic specificity and category analysis of selectors

## When to avoid
- you need actively maintained tooling for modern CSS selectors
- you want full stylesheet linting rather than single-selector analysis

## Facets
- artifact type: library
- maturity: abandoned
- function: parser, developer-tools
- domain: web-development, frontend, developer-tools
- platform: browser
- tags: css-selectors, specificity, performance-analysis, explain-tool, nodejs, javascript

## Member repositories
- josh/css-explain (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:27.429730+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 2026-08-30T06:54:42.897251+00:00, confidence not recorded.
  - readme: https://github.com/josh/css-explain (fetched 2026-08-28T04:03:27.429730+00:00, sha db4d28a1ef2b)
  - homepage: http://josh.github.io/css-explain/ (fetched 2026-08-29T12:56:52.366737+00:00, sha f86b0a60cd7c)
- Data as of 2026-08-30T08:39:29.467469+00:00.