#atom

Subtitle:

A responsiveness metric measuring how quickly a page responds to user interactions

Core Idea:

Interaction to Next Paint (INP) measures the time between when a user interacts with a page (through clicks, taps, or keyboard inputs) and when the browser renders the visual response to that interaction, quantifying real-world responsiveness.

Key Principles:

1. Interaction Latency Measurement:
   • Tracks the delay between user actions and visual feedback, capturing the complete response cycle.
2. Worst-Case Focus:
   • Identifies the slowest interactions rather than averages, highlighting the most frustrating user experiences.
3. Input Types Coverage:
   • Considers various input methods including clicks, taps, keyboard presses, and form interactions.

Why It Matters:

• Perceived Performance:
  • Directly correlates with how responsive an application feels, regardless of initial load speed.
• User Confidence:
  • Fast responses to interactions build trust and confidence in the application.
• Competitive Advantage:
  • Native apps set high responsiveness expectations; web apps must compete with similar responsiveness.

How to Implement:

1. Optimize Event Handlers:
   • Keep JavaScript event handlers lightweight and avoid synchronous, heavy calculations.
2. Implement Visual Feedback:
   • Provide immediate visual cues for interactions even before the full response is ready.
3. Break Up Long Tasks:
   • Split heavy processing into smaller chunks and use techniques like requestAnimationFrame or requestIdleCallback.

Example:

• Scenario:

  • An interactive data dashboard with filterable charts and tables.

• Application:

  • The developer implements optimistic UI updates and task chunking:

  // Instead of this blocking approach
  filterButton.addEventListener('click', () => {
    // Heavy operation blocking the main thread
    const filteredData = heavyDataProcessing(rawData);
    renderAllCharts(filteredData);
  });
  
  // Optimize with this approach
  filterButton.addEventListener('click', () => {
    // Show immediate visual feedback
    setLoadingState(true);
    
    // Schedule the heavy work
    setTimeout(() => {
      // Process data in chunks
      const chunks = splitIntoChunks(rawData, 1000);
      processChunks(chunks, renderProgressively);
    }, 0);
  });
  

• Result:

  • INP improved from 850ms to 120ms, creating a native-app-like experience with immediate visual feedback to user actions.

Connections:

• Related Concepts:
  • First Input Delay (FID): While FID measured only initial input delay, INP provides a more comprehensive view of interaction responsiveness.
  • Long Tasks API: Identifying and breaking up long tasks directly improves INP.
• Broader Concepts:
  • Web Vitals: INP is replacing FID as a Core Web Vital for measuring responsiveness.
  • Perceived Performance Optimization: Creating the feeling of speed even when operations take time.

References:

1. Primary Source:
   • Web.dev INP documentation: https://web.dev/articles/inp
2. Additional Resources:
   • Chrome DevTools Performance panel for identifying slow interactions
   • Sentry's web vitals monitoring for real-user INP tracking

Tags:

#web-performance #user-experience #interactivity #responsiveness #core-web-vitals #frontend #optimization

Connections:

Sources:

• From: Syntax - Explicación de Web Vitals