DOOM SCROLLER

A high-performance, smooth scroll detection library for advanced scroll-based interactions. Part of the CWAVASAPE project.

Features

• 🎯 Precise scroll direction detection
• 📊 Real-time velocity tracking
• 🔄 Smooth scroll delta normalization
• ⚡ High-performance animation frame updates
• 🎛️ Configurable sensitivity and smoothing
• 📱 Cross-browser wheel event normalization
• 💪 Fully typed TypeScript API

Installation

Install the package using your preferred package manager:

# Using npm
npm install @cwavasape/doom-scroller

# Using yarn
yarn add @cwavasape/doom-scroller

# Using pnpm
pnpm add @cwavasape/doom-scroller

Quick Start

import { DoomScroller } from "@cwavasape/doom-scroller";

// Create a new instance
const scroller = new DoomScroller({
  smoothingFactor: 0.2, // Lower = smoother but more latency
  speedMultiplier: 1.5, // Higher = more sensitive
  directionThreshold: 0.1, // Lower = more responsive to direction changes
});

// Initialize scroll detection
scroller.init();

// Subscribe to scroll state updates
const unsubscribe = scroller.subscribe((state) => {
  console.log("Scroll direction:", state.direction);
  console.log("Scroll velocity:", state.velocity);

  if (state.direction.y === "down") {
    // Handle downward scroll
  }
});

// Cleanup when done
scroller.destroy();

Development

If you're working on the CWAVASAPE project locally and want to develop or modify the DOOM SCROLLER package:

Clone the repository

git clone https://github.com/cwavasapee/cwavasape.git
cd cwavasape

Install dependencies

pnpm install

Link the package locally in your package.json

{
  "dependencies": {
    "@cwavasape/doom-scroller": "workspace:*"
  }
}

Run the development environment

pnpm dev

This will start the Turborepo development environment with hot reloading for both the package and any apps consuming it.

API Reference

DoomScroller

Main class for scroll detection and state management.

Constructor Options

interface DoomScrollerOptions {
  /** Multiplier for scroll speed. Default: 1 */
  speedMultiplier?: number;
  /** Number of samples to keep for smoothing. Default: 5 */
  sampleSize?: number;
  /** Minimum velocity to register as movement. Default: 0.1 */
  minVelocity?: number;
  /** Threshold for direction change detection. Default: 0.15 */
  directionThreshold?: number;
  /** Factor for smoothing scroll movements. Default: 0.3 */
  smoothingFactor?: number;
  /** Time in ms to wait before considering scroll ended. Default: 150 */
  debounceTime?: number;
}

Methods

• init(): Initialize scroll detection
• destroy(): Cleanup resources and event listeners
• subscribe(callback: (state: ScrollState) => void): () => void: Subscribe to scroll state updates

Scroll State Interface

interface ScrollState {
  /** Whether scrolling is currently active */
  isScrolling: boolean;
  /** Current velocity in pixels per millisecond */
  velocity: {
    x: number;
    y: number;
  };
  /** Current scroll direction state */
  direction: {
    x: "left" | "right" | "none";
    y: "up" | "down" | "none";
  };
  /** Change in scroll position since last update */
  delta: {
    x: number;
    y: number;
  };
  /** Raw scroll values from the wheel event */
  rawScroll: {
    x: number;
    y: number;
  };
}

Advanced Usage

Smooth Scrolling Animation

const scroller = new DoomScroller({
  smoothingFactor: 0.1, // Very smooth
  speedMultiplier: 1.2,
});

scroller.init();

let translateY = 0;
const content = document.querySelector(".content");

scroller.subscribe((state) => {
  if (!state.isScrolling) return;

  // Apply smooth transform based on velocity
  translateY += state.velocity.y * 16; // 16ms frame time
  content?.style.transform = `translateY(${translateY}px)`;
});

Directional UI Updates

const scroller = new DoomScroller({
  directionThreshold: 0.1, // Responsive to direction changes
});

scroller.init();

const header = document.querySelector(".header");

scroller.subscribe((state) => {
  if (state.direction.y === "up") {
    header?.classList.remove("header--hidden");
  } else if (state.direction.y === "down" && state.velocity.y > 0.5) {
    header?.classList.add("header--hidden");
  }
});

Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Related Packages

Other packages in the CWAVASAPE project:

• @cwavasape/web - Main web application built with SvelteKit 5