Bookmarklet to auto scroll a web page

gistfile1.txt

javascript:(function() {
    // Prompt for scroll speed (pixels per second), default 75
    const speed = prompt('Enter scroll speed (pixels per second):', '75');
    
    if (!speed) return; // Exit if canceled
    
    // Convert speed to pixels per frame (assuming 60fps)
    const pixelsPerFrame = parseFloat(speed) / 60;
    
    // Store initial scroll position
    let currentPosition = window.scrollY;
    
    // Get maximum scroll height
    const maxScroll = Math.max(
        document.body.scrollHeight,
        document.documentElement.scrollHeight,
        document.body.offsetHeight,
        document.documentElement.offsetHeight,
        document.body.clientHeight,
        document.documentElement.clientHeight
    ) - window.innerHeight;
    
    // Scroll function
    function scroll() {
        currentPosition += pixelsPerFrame;
        
        // Stop at the bottom
        if (currentPosition >= maxScroll) {
            return;
        }
        
        window.scrollTo(0, currentPosition);
        requestAnimationFrame(scroll);
    }
    
    // Start scrolling
    scroll();
})();