Replace receptor #6489
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Replace receptor #6489
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- Reduces size of behavior by 66%, minimal component import (accordion) by 50% - Narrows scope to features in use - Avoid baked-in polyfills not necessary for current browser supports - Remove third-party dependencies to reduce maintenance overhead and security vulnerability attack surface area - Add TypeScript annotations for IDEs supporting code autocompletion (e.g. VS Code) ``` echo "import './packages/usa-banner/src/index.js'" | npx esbuild --bundle --minify | brotli-size ``` Before: 1.84 kB After: 896 B Diff: -944 B (-51.3%) ``` echo "import './packages/uswds-core/src/js/utils/behavior'" | npx esbuild --bundle --minify | brotli-size ``` Before: 1.43 kB After: 473 B Diff: -957 B (-66.9%)
Review feedback from #6172
USWDS - Core: Replace receptor library "once" with once option for event listeners
USWDS - Core: Replace receptor library "ignore" with Element#contains
USWDS - Core: Replace receptor library "behavior" with custom implementation
sknep
approved these changes
Jun 12, 2025
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Summary
This PR removes Receptor dependency and reimplements its functionality in first-party code. The only non-dev dependency is now Lit, which is only necessary if using the new web component banner variant.
Breaking change
There are some very niche edge cases highlighted in a separate PR (#5793) that are worth noting here, but if you are only using the public APIs of USWDS components rather than certain internals (as described in the linked PR), breakages are unlikely.
Related issue
Closes #6291
Major changes / Related PRs
The specific replacements/re-implementations for the receptor library functionality are described in greater detail in:
Acknowledgments
Huge thanks to @aduth for doing more than the lion's share of the work on this, and also to our great USWDS alumni, including @mejiaj , @mahoneycm, @amyleadem, @mandylloyd for reviewing and providing feedback on this work along the way.