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Boost UX with NewScroller — Lightning-Fast, Customizable Scrolling

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Getting Started with NewScroller: Installation, API, and Best PracticesNewScroller is a lightweight, modern scrolling library designed to improve user experience by providing smooth, customizable scroll behavior across desktop and mobile browsers. It handles inertia, snap points, virtualized content, and exposes a small, expressive API so developers can tailor scrolling to their app’s needs without sacrificing performance.

Why use NewScroller?

  • Smooth, consistent scrolling across browsers and devices
  • Small footprint — minimal bundle size and few dependencies
  • Customizable behaviors: easing, friction, momentum, and snap points
  • Virtualization support for large lists to reduce DOM cost
  • Accessibility-first — configurable keyboard focus handling and reduced-motion support

Installation

NewScroller is available via npm and CDN.

  • npm (recommended for most projects)

    npm install newscroller

  • Yarn

    yarn add newscroller

  • CDN (for quick prototyping)

    <script src="https://cdn.example.com/newscroller/latest/newscroller.min.js"></script>

After installation, import NewScroller into your JavaScript:

// ESM import NewScroller from 'newscroller'; // CommonJS const NewScroller = require('newscroller');

For frameworks, NewScroller can be used directly or wrapped in a framework-specific component (React/Vue/Svelte). See the examples section for framework usage.

Core Concepts

  • Container: the element that will host the custom scroll behavior (usually a div).
  • Content: the inner element that is scrolled (children of the container).
  • Scroll position: the offset (x, y) that NewScroller manages.
  • Momentum/inertia: how NewScroller continues movement after a user stops dragging.
  • Snap points: discrete positions (e.g., slides or cards) NewScroller can snap to.
  • Virtualization: rendering only visible items in large lists.

Basic Usage

HTML structure:

<div id="scroller" class="scroller">   <div class="scroller-content">     <!-- long list of items -->   </div> </div>

Initialize:

const scroller = new NewScroller(document.getElementById('scroller'), {   direction: 'vertical',    // 'vertical' | 'horizontal' | 'both'   damping: 0.92,            // momentum friction (0..1)   bounce: true,             // allow overscroll bounce   scrollbars: true,         // show custom scrollbars   interactive: true         // enable touch/mouse dragging });

API methods (common):

  • scroller.scrollTo(x, y, options) — animate to position. Options: { duration, easing }.
  • scroller.scrollBy(dx, dy, options) — relative scroll.
  • scroller.getPosition() — returns { x, y }.
  • scroller.on(event, handler) — listen to events (see Events section).
  • scroller.destroy() — remove listeners and restore native behavior.

Configuration Options

Key options with recommended defaults:

  • direction: ‘vertical’ — sets scrolling axis.
  • damping: 0.92 — lower values = quicker stop; keep between 0.85–0.98.
  • bounce: true — toggle overscroll bounce.
  • snap: null | { points: […], threshold: 30, easing: ‘cubic-bezier(…)’ } — enables snap points.
  • virtualize: false | { itemHeight, buffer } — turns on basic virtualization for lists.
  • scrollbar: { visible: true, autoHide: true } — custom scrollbar behavior.
  • keyboard: true — enable arrow/page keys navigation.
  • reducedMotion: ‘auto’ — honors user prefers-reduced-motion setting.

Example with snap:

const scroller = new NewScroller(elem, {   direction: 'horizontal',   snap: {     points: (container) => {       // return array of x offsets for each slide       return Array.from(container.querySelectorAll('.slide')).map((el) => el.offsetLeft);     },     threshold: 40,     easing: 'cubic-bezier(0.22, 1, 0.36, 1)'   } });

Events

NewScroller emits events for integration:

  • ‘scroll’ — fires frequently during scroll with payload { x, y, velocity }
  • ‘scrollStart’ — when user-initiated or programmatic scroll begins
  • ‘scrollEnd’ — when motion stops
  • ‘snap’ — when snap completes with { index, position }
  • ‘reachStart’ / ‘reachEnd’ — when scroll reaches container bounds
  • ‘virtualChange’ — when virtualization adds/removes items

Usage:

scroller.on('scroll', ({ x, y }) => {   // update UI or lazy-load images });

Remove listener:

scroller.off('scroll', handler);

Virtualization (Large Lists)

Virtualization reduces DOM nodes by rendering only visible items.

Initialize virtualization:

const scroller = new NewScroller(listContainer, {   direction: 'vertical',   virtualize: {     itemHeight: 80,     buffer: 3   } });

Implement renderer:

scroller.on('virtualChange', ({ startIndex, endIndex }) => {   renderItems(startIndex, endIndex); });

Tips:

  • Use fixed item heights for best performance. Variable heights are supported but costlier.
  • Keep item renderer idempotent and fast.
  • Combine virtualization with lazy image loading.

Accessibility

  • NewScroller honors prefers-reduced-motion by disabling animations when requested.
  • Keyboard support: arrow keys, PageUp/PageDown, Home/End if keyboard option enabled.
  • Screen readers: ensure content order in DOM remains logical; use aria-live or role attributes for dynamic content updates when necessary.
  • Focus management: when focusing elements inside the scroller, call scroller.scrollIntoView(element, { animate: false }) to avoid disorienting animations.

Example:

scroller.scrollIntoView(document.querySelector('.focused-item'), { animate: false });

Performance Tips

  • Avoid heavy DOM operations during ‘scroll’ events; debounce or use requestAnimationFrame.
  • Prefer transform: translate3d for GPU-accelerated motion.
  • Keep event handlers minimal; use scroller.on(‘scroll’, rAFThrottledHandler).
  • Use virtualization for lists > 100 items.
  • Batch DOM writes and reads to prevent layout thrashing.

Example requestAnimationFrame throttle:

let rafId = null; scroller.on('scroll', (pos) => {   if (rafId) return;   rafId = requestAnimationFrame(() => {     updateProgressBar(pos.y);     rafId = null;   }); });

Common Patterns & Recipes

  • Infinite scroll: listen to ‘reachEnd’ to load more data, then update content and call scroller.refresh().
  • Pull-to-refresh: detect overscroll at start, show spinner, and trigger refresh on release.
  • Carousel with snap: use snap.points derived from slide offsets and listen for ‘snap’ to update indicators.
  • Lazy images: on ‘scroll’, check visible range and load images; better: use IntersectionObserver with virtualization.

Refreshing layout after DOM changes:

// After appending items scroller.refresh(); // recalculates sizes, snap points, virtualization ranges

Troubleshooting

  • Scrolling feels jittery on mobile: ensure touch-action CSS is set correctly (touch-action: pan-y or pan-x), and disable passive listeners when necessary for gestures.
  • Native scrollbars still visible: ensure container has overflow: hidden and NewScroller is initialized on the correct element.
  • Snap not aligning: recalculate snap.points after images/fonts load or call scroller.refresh().

API Reference (Concise)

Methods:

  • new NewScroller(container, options)
  • scrollTo(x, y, { duration = 300, easing = ‘ease’ })
  • scrollBy(dx, dy, opts)
  • getPosition() -> { x, y }
  • scrollIntoView(element, { align = ‘center’, animate = true })
  • refresh()
  • on(event, handler)
  • off(event, handler)
  • destroy()

Events: ‘scroll’, ‘scrollStart’, ‘scrollEnd’, ‘snap’, ‘reachStart’, ‘reachEnd’, ‘virtualChange’

Options: direction, damping, bounce, snap, virtualize, scrollbar, keyboard, reducedMotion

Example: React Integration

Minimal React hook:

import { useEffect, useRef } from 'react'; import NewScroller from 'newscroller'; export default function Scroller({ children }) {   const ref = useRef(null);   const scrollerRef = useRef(null);   useEffect(() => {     scrollerRef.current = new NewScroller(ref.current, { direction: 'vertical' });     return () => scrollerRef.current.destroy();   }, []);   return (     <div ref={ref} className="scroller">       <div className="scroller-content">{children}</div>     </div>   ); }

Best Practices Summary

  • Prefer minimal defaults; only enable features you need (snap, virtualization) to keep complexity low.
  • Respect user preferences for reduced motion.
  • Use virtualization for large lists and batch DOM updates.
  • Keep event handlers lightweight and use rAF for UI updates.
  • Test on real devices—mobile/browser differences matter for touch and performance.

NewScroller aims to be a flexible foundation for modern scroll-driven interfaces. With a small API surface, good defaults, and explicit controls for performance and accessibility, it can handle everything from simple content panes to complex carousels and virtualized feeds.

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