Setting the file. One moment.
Subchapter 2.23
reference/harden.mdMarkdown9 KBView on GitHub
Designs that only work with perfect data aren’t production-ready. Harden the interface against the inputs, errors, languages, and network conditions that real users will throw at it.
Identify weaknesses and edge cases:
Test with extreme inputs:
Test error scenarios:
Test internationalization:
CRITICAL: Designs that only work with perfect data aren’t production-ready. Harden against reality.
Systematically improve resilience:
Long text handling:
/* Single line with ellipsis */
.truncate {
overflow: hidden;
text-overflow: ellipsis;
white-space: nowrap;
}
/* Multi-line with clamp */
.line-clamp {
display: -webkit-box;
-webkit-line-clamp: 3;
-webkit-box-orient: vertical;
overflow: hidden;
}
/* Allow wrapping */
.wrap {
word-wrap: break-word;
overflow-wrap: break-word;
hyphens: auto;
}Flex/Grid overflow:
/* Prevent flex items from overflowing */
.flex-item {
min-width: 0; /* Allow shrinking below content size */
overflow: hidden;
}
/* Prevent grid items from overflowing */
.grid-item {
min-width: 0;
min-height: 0;
}Responsive text sizing:
clamp() for fluid typographyText expansion:
// ❌ Bad: Assumes short English text
<button className="w-24">Submit</button>
// ✅ Good: Adapts to content
<button className="px-4 py-2">Submit</button>RTL (Right-to-Left) support:
/* Use logical properties */
margin-inline-start: 1rem; /* Not margin-left */
padding-inline: 1rem; /* Not padding-left/right */
border-inline-end: 1px solid; /* Not border-right */
/* Or use dir attribute */
[dir="rtl"] .arrow { transform: scaleX(-1); }Character set support:
Date/Time formatting:
// ✅ Use Intl API for proper formatting
new Intl.DateTimeFormat('en-US').format(date); // 1/15/2024
new Intl.DateTimeFormat('de-DE').format(date); // 15.1.2024
new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD'
}).format(1234.56); // $1,234.56Pluralization:
// ❌ Bad: Assumes English pluralization
`${count} item${count !== 1 ? 's' : ''}`
// ✅ Good: Use proper i18n library
t('items', { count }) // Handles complex plural rulesNetwork errors:
// Error states with recovery
{error && (
<ErrorMessage>
<p>Failed to load data. {error.message}</p>
<button onClick={retry}>Try again</button>
</ErrorMessage>
)}Form validation errors:
API errors:
Graceful degradation:
Empty states:
Loading states:
Large datasets:
Concurrent operations:
Interrupted gestures (custom sliders, drag surfaces, scrollable control strips):
pointercancel), capture is lost (lostpointercapture), the pointer is released outside the control, or the window loses focus (blur) mid-drag: clear the dragging state and release capturePermission states:
Browser compatibility:
Client-side validation:
Server-side validation (always):
Constraint handling:
<!-- Set clear constraints -->
<input
type="text"
maxlength="100"
pattern="[A-Za-z0-9]+"
required
aria-describedby="username-hint"
/>
<small id="username-hint">
Letters and numbers only, up to 100 characters
</small>Keyboard navigation:
Screen reader support:
High contrast mode:
Slow connections:
Memory leaks:
Throttling & Debouncing:
// Debounce search input
const debouncedSearch = debounce(handleSearch, 300);
// Throttle scroll handler
const throttledScroll = throttle(handleScroll, 100);Manual testing:
Automated testing:
IMPORTANT: Hardening is about expecting the unexpected. Real users will do things you never imagined.
NEVER:
Test thoroughly with edge cases:
For gestures, say what produced the evidence (emulated viewport, synthesized touch, which engine, physical device) and name what stayed untested.
When edge cases are covered, hand off to /impeccable polish for the final pass.