React Native Bundle DiscoveryCLI
Analyze and compare bundle reports in the terminal or CI.
Requires react-native-bundle-discovery-cli:
yarn add -D react-native-bundle-discovery-cliEvery command takes a metro-stats.json report. An Rsdoctor report or an esbuild metafile works too.
| Command | Description |
|---|---|
analyze | Show recommended optimizations for the bundle |
packages | List all packages in the bundle |
modules | List the heaviest modules |
compare | Compare two reports |
Run any command with --help to see all options:
npx react-native-bundle-discovery-cli --helpanalyze
Shows recommended optimizations, each with an estimated saving: duplicates, deprecated, outdated and dev-only packages, React Native issues with known fixes, and more. It's the default command, so the analyze name can be omitted.
| Option | Values | Description |
|---|---|---|
--format | default (default), json | Output format |
# Recommendations for the bundle
npx react-native-bundle-discovery-cli metro-stats.json
# Same, with the command name
npx react-native-bundle-discovery-cli analyze metro-stats.json
# JSON: each finding also has `sizeInBytes` and the affected `modules`
npx react-native-bundle-discovery-cli metro-stats.json --format json > recommendations.jsonFound 2 recommendations:
Report: metro-stats.json
1. Remove Promise polyfills
Packages: react-native@0.88.0-rc.0
Savings: ~176 Bytes
Why: Bundle contains `react-native/Libraries/Promise.js`.
This file is dead code because Hermes already provides Promise out of the box.
...packages
Lists all packages in the bundle with their versions, paths and sizes. Every installed copy of a package is listed separately, so duplicates are easy to spot.
| Option | Values | Description |
|---|---|---|
--sort | size (default, desc), name (asc) | Sort order |
--format | default (default), table, json | Output format |
# All packages, heaviest first
npx react-native-bundle-discovery-cli packages metro-stats.json
# As a table, sorted by name
npx react-native-bundle-discovery-cli packages metro-stats.json --format table --sort name
# JSON for scripts
npx react-native-bundle-discovery-cli packages metro-stats.json --format json > packages.jsonFound 18 package entries (18 unique names)
Duplicate package names: 0
# | Package | Path | Size
---+---------------------------------------------+----------------------------------------------+----------
1 | react-native@0.88.0-rc.0 | node_modules/react-native | 589.57 KB
2 | @react-native/virtualized-lists@0.88.0-rc.0 | node_modules/@react-native/virtualized-lists | 50.15 KB
3 | whatwg-fetch@3.6.20 | node_modules/whatwg-fetch | 9.82 KBmodules
Lists the heaviest modules of the bundle.
| Option | Values | Description |
|---|---|---|
--limit | number, default 50 | Max number of modules to print. 0 prints all |
--filter | text or /regexp/flags | Keep only modules whose path matches: plain text (case-insensitive) or a regexp |
--sort | size (default, desc), name (asc) | Sort order |
--format | default (default), table, json | Output format |
# Top 50 heaviest modules
npx react-native-bundle-discovery-cli modules metro-stats.json
# Top 10
npx react-native-bundle-discovery-cli modules metro-stats.json --limit 10
# All modules of one package
npx react-native-bundle-discovery-cli modules metro-stats.json --filter node_modules/lodash --limit 0
# Only JSON files, using a regexp
npx react-native-bundle-discovery-cli modules metro-stats.json --filter '/\.json$/i'
# Your own code only, sorted by path
npx react-native-bundle-discovery-cli modules metro-stats.json --filter '/^(?!.*node_modules)/' --sort name --format tableFound 1 of 516 modules matching /\.json$/i - 73 Bytes
1. app.json - 73 Bytescompare
Compares two reports: total size, added, removed and changed modules and packages, version changes, new duplicates and new deprecated packages. The Compare tab of the UI shows the same comparison.
| Option | Values | Description |
|---|---|---|
--before | file, required | Base report, for example from the main branch |
--after | file, required | New report, for example from a pull request |
--limit | number, default 50 | Max number of items per list. 0 prints all |
--format | default (default), markdown, json | Output format. Use markdown for a PR comment |
--fail-on-increase | 50KB, 0.5MB, 51200, 5% | Exit with code 1 if the bundle grows more than the limit |
--max-size | 3MB | Exit with code 1 if the "after" bundle is bigger than the limit |
--fail-on | new-duplicates, new-deprecated | Exit with code 1 if new duplicate and/or deprecated packages appear |
# Diff two reports
npx react-native-bundle-discovery-cli compare --before main-stats.json --after pr-stats.json
# Show every changed module
npx react-native-bundle-discovery-cli compare --before main-stats.json --after pr-stats.json --limit 0
# Markdown report for a PR comment
npx react-native-bundle-discovery-cli compare --before main-stats.json --after pr-stats.json --format markdown > bundle-report.md
# Fail on regressions
npx react-native-bundle-discovery-cli compare --before main-stats.json --after pr-stats.json \
--fail-on-increase 5% \
--max-size 3MB \
--fail-on new-duplicates,new-deprecatedBundle size comparison
Before: main-stats.json
After: pr-stats.json
Summary
Platform: ios
Total size: 852.58 KB → 706.39 KB (-146.18 KB, -17.15%)
Modules: 531 → 516 (-15)
Packages: 18 → 18 (0)
Modules
Added (1, +634 Bytes):
+ node_modules/@babel/runtime/helpers/interopRequireWildcard.js - 634 Bytes
Removed (16, -4.58 KB):
- node_modules/@babel/runtime/helpers/wrapNativeSuper.js - 624 Bytes
... and 15 more. Use --limit <n> to show more (--limit 0 shows all).On GitHub Actions the markdown report is added to the job summary automatically. See Bundle size checks in CI for a full setup.