fec-motion-interaction

Interactive effects

It is suitable for front-end animation tasks that need to design page transitions, scrolling narratives, component introductions, micro-interactions and feedback rhythms into maintainable, degradable and verifiable forms. Load motion-patterns.md when a specific implementation pattern is required.

Purpose

Choose the right animation tools, intensity, and quality gates for your front-end interface.

Procedure

1. Determine animation responsibilities

   • First write down the user intention of the dynamic effect service: positioning, feedback, level changes, status confirmation, narrative guidance or brand memory.
   • The tool-based interface is restrained by default, and priority is given to ensuring scanning efficiency; the marketing page and work page can increase the rhythm, but cannot block the main information.
   • If animation is merely decorative and does not improve understanding, feedback or brand recognition, it should be deleted or replaced with a static visual treatment.
   • Loading, skeleton, toast, error prompts and success feedback belong to status communication; animations can only enhance the feedback rhythm and cannot replace text, semantics or visible status.

2. Choose a technical route

   • CSS transitions/keyframes: hover, focus, toast, simple entry and small status feedback.
   • Framer Motion: React state-driven, layout transitions, list orchestration, and interruptible component-level animations.
   • GSAP: timelines, scroll triggers, complex sequences and precise orchestration across elements.
   • Lottie: The icon or empty state animation output by the design tool is lazy loaded on demand.
   • CSS scroll-driven animation: Use when progressive enhancement is acceptable and legacy browser consistency is not required.

3. Define intensity levels

   • Level 1-2: Only uses 150-250ms opacity/transform, suitable for background, forms and high-frequency tools.
   • Level 3-4: Add short stagger, partial spring and lightweight reveal, suitable for dashboards, settings pages and management consoles.
   • Level 5-6: Add parallax, layout morph, and pointer response, suitable for product display and interactive homepage.

• Level 7+: To use scrolling narrative, fixed paragraphs or 3D/WebGL cooperation, the mobile version and reduced-motion downgrade must be done separately.
  • Scenario default values: public services, medical, financial and highly accessible products start from Level 1-2; SaaS tools and data backends start from Level 2-3; marketing pages, brand pages and portfolios can start from Level 4-6; only experimental activity pages or immersive narratives can consider Level 7+.
  • If the UI design process already has a motion intensity dial set up, use that dial; don’t automatically increase the intensity just because a certain motion library is introduced.

4. Establish performance boundaries
   • Only high-frequency animations transform, opacity, use filter and clip-path with caution.
   • GSAP, Lottie, Three.js, heavy animation components must be dynamically imported or isolated in leaf components.

• Sustained animations require pause conditions: invisible, tab hidden, user closed, low battery, or reduced motion.
  • Do not read and write layout synchronously on scroll events; use IntersectionObserver, ScrollTimeline, or throttled rAF.
  • Scroll narrative, stagger, spring, magnetic pointer and parallax effects must have clear responsibilities respectively; do not stack multiple high-intensity motion languages on the same screen at the same time.
  • The rhythm of repeated reveal animations on long pages must be controlled to avoid each block entering with the same delay, direction, and easing, causing a template feel and scrolling fatigue.

5. Design for accessible degradation

   • All non-essential motion effects read prefers-reduced-motion and downgrade to static, fade-in or instant state.
   • If the automatic playback or looping animation exceeds 5 seconds, a pause method should be provided or it should only run in local non-critical areas.
   • Do not flash more than 3 times per second; do not use animation as the only status reminder.
   • The focus ring, error prompt, and success feedback must be equally clear when there is no animation.
   • Gesture animations must be replaced by clicks, keyboards, or explicit controls; dragging, sliding, and long-pressing cannot be the only operation paths.

6. Verify delivery

   • Check whether the animation blocks the copy, button or table content at 375px, 768px, and 1440px.
   • Check whether the first loaded bundle is significantly bloated by the animation library.
   • Turn on reduced motion manually and confirm that the animation is disabled or weakened.
   • Confirm scrolling and key interactions without noticeable frame drops using the performance panel or actual device.
   • Check that the animation intensity matches the page type: the workbench should not have a marketing-style scrolling theater, and the portfolio should not only have a default hover fade-in.
   • Verify that scroll trigger sequences allow users to reach content quickly without losing context due to pinned blocks, long timelines, or uninterruptible transitions.

Constraints

• Do not mix Framer Motion and GSAP controls for the same element within the same component.
• Don’t use animations to cover up missing statuses such as loading, empty, error, disabled, etc.
• Do not add large parallax or scroll hijacking by default for ordinary background tables, configuration pages and high-frequency workbench.
• Do not use the same reveal template for all blocks; the rhythm of the animation should vary with the information level and user tasks.
• Do not animate width, height, top, left, margin, padding and other properties that frequently trigger layout.
• Do not put large Lottie JSON, GSAP plug-ins or 3D scenes into the above-the-fold sync package.
• Don't let animations change reading order, focus order, or keyboard accessibility.
• Do not use skeleton for a long time to cover up the actual loading failure; when it exceeds expectations, it should be transferred to an understandable loading, retry or error state.

Expected Output

The output should include animation purpose, technology selection, intensity level, degradation strategy, performance boundaries and verification results. Post-completion interactions help users understand state and hierarchy, remain available on reduced-motion and low-end devices, and do not significantly slow down the above-the-fold or scrolling experience.