baseline-check (blc)

Lightweight CLI to scan a project for used web platform features and report their Baseline status (via web-features) with line number precision.

Quick start

• One-off (no install):

npx baseline-check

• Install locally (dev):

npm install --save-dev baseline-check
npx baseline-check

• Install globally:

npm install -g baseline-check
baseline-check

Usage examples

• Default (scan project, show risky items with line numbers):

  npx baseline-check

• Show everything:

  npx baseline-check --all

• Show newly available features:

  npx baseline-check --new

• Summary only (summary implies --all):

  npx baseline-check --summary

• Group by feature category:

  npx baseline-check --group

• JSON output for tooling integration:

  npx baseline-check --json

• Show features baseline since a specific date:

  npx baseline-check --since 2023-01-01

• Scan specific files/globs:

  npx baseline-check src/**/*.css

Flags

• --all Show all findings
• --new Show newly available features
• --warnings, -w Show warnings + newly available
• --summary, -s Print summary counts and score (implies --all)
• --json Output in JSON format for tooling
• --group Group findings by feature category (CSS, Grid, etc.)
• --since DATE Show features baseline since date (YYYY-MM-DD format)
• --limit N Limit printed items per file/group

Features

• Line-precise detection: Shows exact line numbers where features are used
• Multi-format support: Scans CSS, HTML, JavaScript/TypeScript files
• Inline code detection: Finds features in inline styles and script tags
• Feature grouping: Organize results by web platform categories
• Date filtering: Track baseline adoption trends over time
• JSON export: Machine-readable output for IDE and tooling integration
• Comprehensive coverage: Uses web-features data and compute-baseline

Output Examples

Standard Report

File: src/styles.css
─────────────────────────────────────────────
Feature             Line Status      Support
─────────────────────────────────────────────
Grid                3    ✅ Widely    Baseline 2020-04-17
Subgrid             4    🟡 Newly     Baseline 2023-09-15
word-break: auto-p  10   ❌ Not in    chrome, chrome_android, edge

Grouped Report (--group)

Group: Grid
─────────────────────────────────────────────
Feature             Line File            Status      Support
─────────────────────────────────────────────
Grid                3    styles.css      ✅ Widely    Baseline 2020-04-17
Subgrid             4    styles.css      🟡 Newly     Baseline 2023-09-15

Notes

• CLI names: blc and baseline-check (both point to the same binary)
• The launcher strips a single -- automatically, so both npx . --summary and npx . -- --summary work
• Scanner ignores node_modules, dist, and .git by default
• Set BLC_DEBUG=1 to print the resolved args for debugging:

$env:BLC_DEBUG=1; npx . --summary

Publishing / testing

• Preview publish contents:

npm pack --dry-run
npm publish --dry-run

• Dev/test files (e.g. debug-bcd.js, debug-parse-css.js, test-sample.css) are for local testing and should not be included in the published package. The files field in package.json restricts published files.

• Publish a patch (recommended flow):

npm version patch -m "chore(release): %s"
npm publish --access public
git push && git push --tags

License

ISC