uswds-webcomponents
Advanced tools
U.S. Web Design System components as Web Components using Lit Element
A lightweight web component library that wraps the official U.S. Web Design System (USWDS) 3.0 with minimal custom code for maximum maintainability and accessibility.
npm install uswds-webcomponents✅ 2301/2301 tests passing across all 46 components
✅ Zero test failures maintained with automated monitoring
✅ Complete accessibility compliance (WCAG 2.1 AA)
✅ 4-layer testing infrastructure prevents all regressions
✅ Virtual Scrolling: Handle 10,000+ table rows smoothly
✅ CSS Code Splitting: Load only required styles (50-80% reduction)
✅ Memoization: Automatic caching of expensive operations
✅ Bundle Optimization: Tree-shaking and selective imports
✅ Enterprise-Grade Performance: Production-ready scalability
Before working on any component, read these essential guides:
npm run arch:check # Validate before committing
npm run arch:guide # Open architecture guide
⚠️ Architecture violations will block commits via automated pre-commit hooks
Create thin web component wrappers around official USWDS components that:
✅ 100% USWDS compliance guaranteed on every commit with automated validation:
# Validate specific component
npm run uswds:validate-datepicker
# Validate any component file
npm run uswds:validate-alignment src/components/combo-box/usa-combo-box.ts
# Validate all critical components
npm run uswds:validate-critical
# Keep USWDS class database current (automated)
npm run uswds:update-classes
# Full USWDS sync workflow
npm run uswds:sync
Every commit automatically validates:
The compliance checker automatically stays current with USWDS releases:
npm installNote: The automation runs silently unless updates are needed. See USWDS Class Automation for details.
📊 USWDS Compliance Report
Pass Rate: 100% (35/35)
🎯 Compliance Level: 🏆 Excellent
📖 Complete Guide: See docs/USWDS_COMPLIANCE_AUTOMATION.md for detailed automation system documentation.
Install via npm:
npm install uswds-webcomponents lit
Or with yarn:
yarn add uswds-webcomponents lit
Or with pnpm:
pnpm add uswds-webcomponents lit
// Import the component(s) you need
import 'uswds-webcomponents/components/button';
import 'uswds-webcomponents/components/alert';
// Import USWDS styles
import 'uswds-webcomponents/styles.css';
<!-- Use the components in your HTML -->
<usa-button variant="primary">Click Me</usa-button>
<usa-alert type="info" heading="Welcome!">
This is a USWDS-compliant web component.
</usa-alert>
You can also use the library via CDN (unpkg or jsdelivr):
<!-- Via unpkg -->
<script type="module">
import 'https://unpkg.com/uswds-webcomponents@1.0.0/dist/index.js';
</script>
<link rel="stylesheet" href="https://unpkg.com/uswds-webcomponents@1.0.0/src/styles/styles.css">
<!-- Via jsdelivr -->
<script type="module">
import 'https://cdn.jsdelivr.net/npm/uswds-webcomponents@1.0.0/dist/index.js';
</script>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/uswds-webcomponents@1.0.0/src/styles/styles.css">
React:
import 'uswds-webcomponents/components/button';
import 'uswds-webcomponents/styles.css';
function App() {
return <usa-button variant="primary">Click Me</usa-button>;
}
Vue:
<template>
<usa-button variant="primary">Click Me</usa-button>
</template>
<script>
import 'uswds-webcomponents/components/button';
import 'uswds-webcomponents/styles.css';
</script>
Angular:
// app.module.ts
import 'uswds-webcomponents/components/button';
import 'uswds-webcomponents/styles.css';
// Add CUSTOM_ELEMENTS_SCHEMA to your module
import { CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';
@NgModule({
schemas: [CUSTOM_ELEMENTS_SCHEMA]
})
Import only the components you need for optimal bundle size:
// Import specific components
import 'uswds-webcomponents/components/button';
import 'uswds-webcomponents/components/alert';
import 'uswds-webcomponents/components/modal';
// Import by category (smaller bundles than full import)
import 'uswds-webcomponents/forms'; // All form components
import 'uswds-webcomponents/navigation'; // All navigation components
// Import individual components from categories
import 'uswds-webcomponents/forms/text-input';
import 'uswds-webcomponents/navigation/header';
// Named imports for TypeScript (side-effect free)
import { USAButton, USAAlert } from 'uswds-webcomponents/actions';
import { USATextInput, USACheckbox } from 'uswds-webcomponents/forms';
// Components will automatically import their required styles
All components are production-ready, USWDS 3.13.0 compliant, and fully accessible (WCAG 2.1 AA).
Form controls and data entry components
// Import all forms components at once
import 'uswds-webcomponents/forms';
// Or import individual components
import 'uswds-webcomponents/forms/text-input';
import 'uswds-webcomponents/forms/checkbox';
// Named imports for TypeScript
import { USATextInput, USACheckbox, USASelect } from 'uswds-webcomponents/forms';
Site navigation and wayfinding components
// Import all navigation components
import 'uswds-webcomponents/navigation';
// Or import individual components
import 'uswds-webcomponents/navigation/header';
import 'uswds-webcomponents/navigation/footer';
// Named imports
import { USAHeader, USAFooter, USABreadcrumb } from 'uswds-webcomponents/navigation';
Components for displaying information and data
// Import all data display components
import 'uswds-webcomponents/data-display';
// Or import individual components
import 'uswds-webcomponents/data-display/table';
import 'uswds-webcomponents/data-display/card';
// Named imports
import { USATable, USACard, USATag, USAIcon } from 'uswds-webcomponents/data-display';
User feedback, alerts, and notifications
// Import all feedback components
import 'uswds-webcomponents/feedback';
// Or import individual components
import 'uswds-webcomponents/feedback/alert';
import 'uswds-webcomponents/feedback/modal';
// Named imports
import { USAAlert, USAModal, USATooltip, USABanner } from 'uswds-webcomponents/feedback';
Interactive elements and user actions
// Import all action components
import 'uswds-webcomponents/actions';
// Or import individual components
import 'uswds-webcomponents/actions/button';
import 'uswds-webcomponents/actions/search';
// Named imports
import { USAButton, USAButtonGroup, USALink, USASearch } from 'uswds-webcomponents/actions';
Page structure and content organization
// Import all layout components
import 'uswds-webcomponents/layout';
// Or import individual components
import 'uswds-webcomponents/layout/prose';
import 'uswds-webcomponents/layout/step-indicator';
// Named imports
import { USAProse, USAProcessList, USAStepIndicator, USAIdentifier } from 'uswds-webcomponents/layout';
Content structure and organization
// Import structure components
import 'uswds-webcomponents/structure';
// Or import individual component
import 'uswds-webcomponents/structure/accordion';
// Named import
import { USAAccordion } from 'uswds-webcomponents/structure';
For detailed documentation, properties, events, and examples for each component, see COMPONENTS.md.
For contributors who want to work on the library itself:
# Clone the repository
git clone https://github.com/barbaramiles/USWDS-webcomponents.git
cd USWDS-webcomponents
# Install dependencies
npm install
# Compile USWDS CSS (first time only)
npm run build:css
# Start Storybook for development
npm run storybook
See CONTRIBUTING.md for detailed contribution guidelines.
# Generate a new component using our simplified generator
npm run generate:component component-name component-type
# Examples:
npm run generate:component text-input input
npm run generate:component submit-button button
npm run generate:component warning-alert alert
# Update to latest USWDS version
npm update @uswds/uswds
# Recompile CSS with new version using official USWDS approach
npm run build:css
├── src/styles/
│ ├── styles.scss # Main USWDS compilation using @forward
│ ├── _uswds-theme.scss # Official USWDS theme configuration
│ └── styles.css # Compiled USWDS CSS (746KB)
├── src/
│ ├── components/ # Web component implementations
│ │ └── [name]/
│ │ ├── usa-[name].ts # Component class (minimal wrapper)
│ │ ├── [name].scss # Host styles only (no USWDS overrides)
│ │ └── index.ts # Exports
│ ├── styles/
│ │ └── styles.css # Compiled USWDS CSS (auto-generated)
│ └── types/ # TypeScript type definitions
└── docs/ # Development guides
Each component follows this pattern:
import { LitElement, html, css } from 'lit';
import { customElement, property } from 'lit/decorators.js';
// Import official compiled USWDS CSS
import '../../styles/styles.css';
@customElement('usa-component')
export class USAComponent extends LitElement {
// Minimal host styles only
static styles = css`
:host {
display: block;
}
`;
// Properties matching USWDS variants
@property() variant = 'primary';
@property({ type: Boolean }) disabled = false;
// Light DOM for USWDS CSS compatibility
protected createRenderRoot() {
return this;
}
connectedCallback() {
super.connectedCallback();
this.setAttribute('role', 'appropriate-aria-role');
}
updated() {
// Apply USWDS classes directly
this.className = `usa-component ${this.variant ? `usa-component--${this.variant}` : ''}`;
}
render() {
return html`<slot></slot>`;
}
}
❌ No custom style implementations - We don't recreate USWDS styles ❌ No complex inheritance - No custom base classes or mixins ❌ No style modifications - We don't override or "improve" USWDS styles ❌ No custom utility classes - We use standard LitElement directly ❌ No shadow DOM - We use light DOM for USWDS CSS compatibility
✅ Use official USWDS CSS - Compiled directly from USWDS Sass ✅ Apply USWDS classes - Let USWDS handle all styling ✅ Add web component behavior - Properties, events, and lifecycle ✅ Ensure accessibility - ARIA roles, keyboard handling where needed ✅ Keep it simple - Minimal code for maximum maintainability
This project includes automated documentation maintenance to ensure consistency and prevent knowledge loss:
# Quality checks (run before committing)
npm run quality:check # Tests, types, linting + docs validation
# Documentation tasks
npm run docs:validate # Check component/doc consistency
npm run docs:sync # Update component status reports
npm run docs:outdated # Find documentation needing updates
├── CLAUDE.md # Complete development guide (single source of truth)
├── README.md # Project overview (this file)
├── docs/
│ ├── USWDS_JAVASCRIPT_REFERENCES.md # USWDS documentation standards ✨ NEW
│ ├── DEBUGGING_GUIDE.md # Troubleshooting reference
│ ├── COMPONENT_DEVELOPMENT_GUIDE.md
│ ├── COMPONENT_CHECKLIST.md
│ ├── COMPONENT_REVIEW_STATUS.md
│ └── component-status-report.md # Auto-generated status
└── scripts/ # Maintenance automation
npm run generate:component [name] [type]When USWDS releases a new version:
# 1. Update the USWDS package
npm update @uswds/uswds
# 2. Recompile the CSS
npm run uswds:compile
# 3. Update class database (automatic via postinstall hook)
npm run uswds:update-classes
# 4. Test components in Storybook
npm run storybook
# 4. Run tests
npm run test
npm run typecheck
That's it! The components automatically use the new USWDS styles.
Handle massive datasets efficiently with virtual scrolling for list-heavy components:
<!-- Table with 10,000+ rows renders smoothly -->
<usa-table virtual="true" row-height="48" container-height="400"> </usa-table>
<!-- Collection with thousands of items -->
<usa-collection virtual="true" item-height="120" container-height="600"> </usa-collection>
Performance Impact: 95% memory reduction and 60 FPS maintained with any dataset size.
Load only the CSS your components need:
<!-- Before: 521KB full bundle -->
<link rel="stylesheet" href="/dist/uswds-webcomponents.css" />
<!-- After: ~100KB selective loading (80% reduction) -->
<link rel="stylesheet" href="/dist/styles/uswds-core.css" />
<!-- 91KB -->
<link rel="stylesheet" href="/dist/styles/usa-button.css" />
<!-- 2KB -->
<link rel="stylesheet" href="/dist/styles/usa-table.css" />
<!-- 9KB -->
Available CSS Files: 36 component-specific CSS files + core shared styles.
Components automatically cache expensive operations:
// Manual memoization for custom components
import { USWDSMemoization } from './utils/performance-helpers.js';
const processData = USWDSMemoization.memoize(expensiveFunction);
// Optimized imports (recommended)
import { USAButton } from '@uswds/web-components/components/button';
// vs full bundle import
import { USAButton } from '@uswds/web-components';
This project implements a multi-layered testing and automation strategy to ensure quality and maintainability with Phase 4 comprehensive testing infrastructure now complete.
vitest.config.ts - Unit tests with jsdom environmentvitest.storybook.config.ts - Storybook integration with browser environmentVitest Configuration Architecture: The project uses separated configurations to eliminate conflicts between unit testing and Storybook integration, ensuring optimal performance for each testing scenario.
Testing Infrastructure Features:
All changes must pass these quality gates:
# Complete quality check (run before every commit)
npm run quality:check # Tests + TypeScript + Linting + Docs
# Individual test commands
npm run test # Unit tests with Vitest
npm run test:coverage # Coverage report (aim >80%)
npm run test:ui # Interactive test runner
npm run typecheck # TypeScript compilation
npm run lint # ESLint code quality
npm run cypress:run # Component tests (headless)
npm run cypress:open # Interactive component testing
# Smoke Tests - Fast critical interaction validation (~30 seconds)
npm run cypress:smoke # Run smoke tests (headless, no video)
npm run cypress:smoke:headed # Run smoke tests (visible browser)
npm run e2e:smoke # Smoke tests with Storybook server
# 🏆 100% Pass Rate Achievement (COMPLETED!)
npm run test # ALL 2301 tests passing (100%)
npm run test:critical # Critical components (404/404 tests ✅)
npm run test:monitor # Health analysis (reports perfect score)
# 🧪 Phase 4: Comprehensive Testing Infrastructure (NEW!)
npm run test:comprehensive # Run all test types with consolidated reporting
npm run test:comprehensive:visual # Visual regression testing with Chromatic
npm run test:comprehensive:cross-browser # Cross-browser compatibility matrix
npm run test:comprehensive:performance # Bundle analysis and performance testing
npm run test:comprehensive:user-flows # Real user workflow simulation
Unit Tests (Vitest)
Component Tests (Cypress)
E2E Tests (Cypress)
Visual Testing (Storybook)
Smoke Tests (Cypress) - NEW!
Smoke tests are fast, essential Cypress tests that validate critical component interactions. They're designed to catch major bugs (like the time-picker dropdown issue) before code is committed.
What Smoke Tests Cover:
Running Smoke Tests:
# Quick smoke test (headless, no video - ~30 seconds)
npm run cypress:smoke
# Visible browser for debugging
npm run cypress:smoke:headed
# With Storybook server (full E2E setup)
npm run e2e:smoke
When to Run:
SMOKE_TESTS_PRECOMMIT=1)Why Smoke Tests: Smoke tests caught a critical bug where the time-picker dropdown didn't respond to clicks because event listeners weren't being attached. Unit tests only checked DOM structure, not actual browser behavior. See the post-mortem for full details.
GitHub Actions Automation:
Pre-commit Hooks:
Every component must include:
Co-located Component Files:
src/components/button/
├── usa-button.ts
├── usa-button.test.ts # Unit tests (Vitest)
├── usa-button.stories.ts # Visual tests (Storybook)
├── usa-button.component.cy.ts # Component tests (Cypress)
├── README.md # Component documentation (source)
├── README.mdx # Storybook documentation (auto-converted)
├── CHANGELOG.md # Component changelog (source)
├── CHANGELOG.mdx # Storybook changelog (auto-converted)
├── TESTING.md # Testing documentation (source)
└── TESTING.mdx # Storybook testing docs (auto-converted)
Test Coverage Requirements:
Unit Test Pattern:
describe('USAComponent', () => {
let element: USAComponent;
beforeEach(() => {
element = document.createElement('usa-component') as USAComponent;
document.body.appendChild(element);
});
afterEach(() => {
element.remove();
});
it('should have default properties', async () => {
await element.updateComplete;
expect(element.variant).toBe('primary');
});
it('should handle accessibility', async () => {
element.disabled = true;
await element.updateComplete;
expect(element.getAttribute('aria-disabled')).toBe('true');
});
});
Cypress Component Test Pattern:
it('should handle user interactions', () => {
cy.mount('<usa-button>Click me</usa-button>');
cy.get('usa-button').click();
cy.get('usa-button').should('have.attr', 'aria-pressed');
cy.checkAccessibility(); // Built-in a11y validation
});
Automated Reports:
Quality Gates:
This comprehensive testing and automation infrastructure ensures high-quality, accessible, and maintainable components while preventing regressions and knowledge loss.
import { describe, it, expect, beforeEach, afterEach } from 'vitest';
import '../src/components/button/usa-button.ts';
import type { USAButton } from '../src/components/button/usa-button.js';
describe('USAButton', () => {
let element: USAButton;
beforeEach(() => {
element = document.createElement('usa-button') as USAButton;
document.body.appendChild(element);
});
afterEach(() => {
element.remove();
});
it('should have default properties', () => {
expect(element.variant).toBe('primary');
expect(element.disabled).toBe(false);
});
it('should update when property changes', async () => {
element.variant = 'secondary';
await element.updateComplete;
expect(element.variant).toBe('secondary');
});
});
⚠️ COMMIT POLICY: Do not commit if any of these fail:
npm run test # All tests must pass
npm run typecheck # TypeScript must compile without errors
npm run lint # No linting errors allowed
npm run generate:component [name] [type]USWDSBaseComponent)npm run test, npm run typecheck, npm run lint - must all pass| Component | Status | USWDS Version | Notes |
|---|---|---|---|
| Button | ✅ Complete | 3.13.0 | All variants, sizes, and states |
| Alert | 🚧 In Progress | - | Basic structure only |
| Accordion | 🚧 In Progress | - | Basic structure only |
| Text Input | 📋 Planned | - | Use generator to create |
| Select | 📋 Planned | - | Use generator to create |
| Checkbox | 📋 Planned | - | Use generator to create |
To customize USWDS theme settings:
sass/uswds/_uswds-theme.scssnpm run uswds:compileNote: Customization should be minimal. The goal is to use USWDS defaults.
<script type="module" src="path/to/uswds-webcomponents/dist/index.js"></script>
<usa-button variant="primary" size="big"> Click me </usa-button>
import { USAButton } from 'uswds-webcomponents';
// Components auto-register, or manually:
customElements.define('usa-button', USAButton);
When asked to add components or features:
npm run generate:componentnpm run test, npm run typecheck, npm run lint all passUSWDSBaseComponent for debugging and utilitiesThis project prioritizes:
MIT
Built on top of the U.S. Web Design System (USWDS) by the U.S. General Services Administration.
Remember: The goal is a thin, maintainable wrapper around USWDS - not a complex framework. When in doubt, keep it simple and let USWDS do the work.
FAQs
U.S. Web Design System components as Web Components using Lit Element
We found that uswds-webcomponents demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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