ScrollManager

Overview

ScrollManager is the scroll behavior management system in Now.js Framework. It supports smooth scrolling, waypoints, scroll tracking, and infinite scroll.

When to use:

• Need smooth scroll to element
• Need scroll waypoints/triggers
• Need infinite scroll
• Need scroll restoration
• Need scroll navigation

Why use it:

• ✅ Smooth scrolling with easing
• ✅ Waypoints and triggers
• ✅ Infinite scroll support
• ✅ Scroll position persistence
• ✅ Mobile touch support
• ✅ Accessibility features

Basic Usage

Initialization

await ScrollManager.init({
  enabled: true,
  smoothScroll: {
    enabled: true,
    selector: 'a[href^="#"]'
  }
});

Smooth Scroll to Element

// Scroll to element
await ScrollManager.scrollTo('#section-2');

// With options
await ScrollManager.scrollTo('#contact', {
  offset: -100,    // Offset from top
  duration: 800,   // Animation duration
  easing: 'easeInOutCubic'
});

Scroll to Position

// Scroll to top
await ScrollManager.scrollToTop();

// Scroll to bottom
await ScrollManager.scrollToBottom();

// Scroll to specific position
await ScrollManager.scrollTo(500);  // 500px from top

Configuration

await ScrollManager.init({
  enabled: true,

  core: {
    offset: 0,              // Global offset
    duration: 500,          // Default animation duration
    easing: 'easeInOutCubic'
  },

  smoothScroll: {
    enabled: true,
    selector: 'a[href^="#"]',
    excludeSelector: '.no-smooth',
    hashChangeEnabled: true
  },

  waypoints: {
    enabled: true,
    threshold: 0.5,         // Visibility threshold
    offset: '0px'
  },

  infiniteScroll: {
    enabled: false,
    threshold: 0.9
  },

  persistence: {
    enabled: true,
    key: 'scroll_positions'
  },

  mobile: {
    enabled: true,
    touchAction: 'pan-y',
    momentumScroll: true
  }
});

API Reference

ScrollManager.scrollTo(target, options)

Scroll to target

Returns: Promise<void>

await ScrollManager.scrollTo('#features', {
  offset: -80,
  duration: 600
});

ScrollManager.scrollToTop(options)

Scroll to top

await ScrollManager.scrollToTop({ duration: 500 });

ScrollManager.scrollToBottom(options)

Scroll to bottom

await ScrollManager.scrollToBottom();

ScrollManager.scrollToContent(options)

Scroll to main content

await ScrollManager.scrollToContent();

ScrollManager.getScrollPosition()

Get current position

Returns: Object - { x, y, direction }

const pos = ScrollManager.getScrollPosition();
console.log(`Scroll Y: ${pos.y}`);

ScrollManager.addWaypoint(id, element, options)

Add waypoint

ScrollManager.addWaypoint('section-1', document.getElementById('section-1'), {
  onEnter: () => console.log('Section 1 visible'),
  onLeave: () => console.log('Section 1 hidden'),
  threshold: 0.5
});

ScrollManager.removeWaypoint(id)

Remove waypoint

ScrollManager.removeWaypoint('section-1');

ScrollManager.cancelScroll()

Cancel current animation

ScrollManager.cancelScroll();

Easing Functions

Events

EventManager.on('waypoint:enter', (data) => {
  console.log(`${data.id} is now visible`);
});

Real-World Examples

Smooth Anchor Links

<nav>
  <a href="#home">Home</a>
  <a href="#features">Features</a>
  <a href="#pricing">Pricing</a>
  <a href="#contact">Contact</a>
</nav>

<section id="home">...</section>
<section id="features">...</section>
<section id="pricing">...</section>
<section id="contact">...</section>

<script>
await ScrollManager.init({
  enabled: true,
  smoothScroll: {
    enabled: true,
    selector: 'a[href^="#"]'
  }
});
</script>

Back to Top Button

<button id="back-to-top" class="hidden">↑</button>

<script>
const button = document.getElementById('back-to-top');

// Show/hide based on scroll position
window.addEventListener('scroll', () => {
  button.classList.toggle('hidden', window.scrollY < 300);
});

button.addEventListener('click', () => {
  ScrollManager.scrollToTop({ duration: 400 });
});
</script>

Active Section Highlighting

const sections = document.querySelectorAll('section[id]');
const navLinks = document.querySelectorAll('nav a');

sections.forEach(section => {
  ScrollManager.addWaypoint(section.id, section, {
    threshold: 0.3,
    onEnter: () => {
      navLinks.forEach(link => {
        link.classList.toggle('active',
          link.getAttribute('href') === `#${section.id}`
        );
      });
    }
  });
});

Lazy Load Images

const images = document.querySelectorAll('img[data-src]');

images.forEach((img, index) => {
  ScrollManager.addWaypoint(`lazy-${index}`, img, {
    threshold: 0.1,
    onEnter: () => {
      img.src = img.dataset.src;
      img.removeAttribute('data-src');
      ScrollManager.removeWaypoint(`lazy-${index}`);
    }
  });
});

Common Pitfalls

⚠️ 1. Wait for Init

// ❌ Using before init
ScrollManager.scrollTo('#section');

// ✅ Wait for init
await ScrollManager.init({ enabled: true });
ScrollManager.scrollTo('#section');

⚠️ 2. Offset for Fixed Header

// ❌ Not accounting for header
ScrollManager.scrollTo('#content');

// ✅ Add offset
const headerHeight = document.querySelector('header').offsetHeight;
ScrollManager.scrollTo('#content', {
  offset: -headerHeight
});

Related Documentation

• AnimationManager - Animations
• RouterManager - SPA routing