implementation-debugging

Implementation Debugging

Debug animation issues using Disney's principles as diagnostic framework.

Problem Indicators

• Animation doesn't play at all
• Animation plays but looks wrong
• Works in dev, broken in production
• Inconsistent across browsers
• Animation triggers at wrong time
• Flickering or visual glitches

Diagnosis by Principle

Timing

Issue: Animation timing is off Debug: Check duration values. Verify units (ms vs s). Check if CSS transition is being overridden. Inspect computed styles.

Straight Ahead vs Pose-to-Pose

Issue: Keyframes not hitting Debug: Verify all keyframe percentages. Check for typos in property names. Ensure values are animatable.

Staging

Issue: Animation hidden or clipped Debug: Check z-index, overflow, opacity. Verify element is in viewport. Check for visibility: hidden.

Solid Drawing

Issue: Visual glitches during animation Debug: Look for subpixel rendering issues. Add transform: translateZ(0) for GPU layer. Check for layout thrashing.

Follow Through

Issue: Animation ends abruptly or wrong state Debug: Check animation-fill-mode. Verify end state matches CSS. Check for competing animations.

Common Bugs

Symptom	Likely Cause	Fix
No animation	Property not animatable	Use transform instead of changing property directly
Flicker at start	No initial state	Set initial values explicitly
Wrong end state	Fill mode	Add forwards to animation
Choppy motion	Layout thrashing	Animate only transform/opacity
Works once only	Animation not reset	Remove and re-add class, or use JS

Quick Fixes

1. Check DevTools Animation panel - See timeline
2. Verify animatable properties - Not all CSS animates
3. Add animation-fill-mode: forwards - Keep end state
4. Force GPU layer - will-change: transform
5. Check for !important - May override animation

Troubleshooting Checklist

• Is animation class/trigger being applied? (DevTools Elements)
• Are properties animatable? (display is not, opacity is)
• Check computed styles for overrides
• Is element visible? (opacity, visibility, display, z-index)
• Any JavaScript errors blocking execution?
• Check Animation panel in DevTools
• Test in incognito (no extensions)
• Compare working vs broken environment

Code Pattern

// Debug: Log animation events
element.addEventListener('animationstart', (e) => {
  console.log('Animation started:', e.animationName);
});

element.addEventListener('animationend', (e) => {
  console.log('Animation ended:', e.animationName);
});

// Debug: Check computed animation
const styles = getComputedStyle(element);
console.log('Animation:', styles.animation);
console.log('Transition:', styles.transition);

// Reset animation
element.classList.remove('animate');
void element.offsetWidth; // Trigger reflow
element.classList.add('animate');

DevTools Tips

1. Elements > Styles: Check computed animation values
2. Performance tab: Record and analyze frames
3. Animations panel: Slow down, replay, inspect
4. Console: Log animation events