Vanilla JS smooth scrolling

smoothscroll.js

/**
 * Vanilla JS smooth scrolling
 * 
 * @version   0.1b1
 * @author    Lukas Bestle <[email protected]>
 * @copyright Lukas Bestle
 * @license   http://www.opensource.org/licenses/mit-license.php MIT License
 */

// Configuration
var max = 50;   // How many maximum steps
var time = 300; // How many milliseconds?

var smoothScroll = function(element, pixels, count) {
  // Increase recursion count
  count += 1;
	
	// Check if it scrolled to often (maybe the user scrolled manually or so)
	if(count > max) {
		return;
	}
	
	// Get the current positions
	var container = element.parentNode;
	var current = container.scrollTop;
	var destination = element.offsetTop;
	
	if(destination == current) {
		// Finished, set hash
		setTimeout(function() {
			if(element.id) window.location.hash = element.id;
		}, 100);
		
		return;
	}
	
	// Calculate difference per step (20 steps)
	if(!pixels) pixels = parseInt((destination - current) / 20, 10);
	
	// Check how near we are and reduce the speed over time (easing, yehaa!)
	var pixelsAbs = Math.abs(pixels);
	if(Math.abs(destination - current) < 2 * pixelsAbs && pixelsAbs > 1) pixels = parseInt(pixels / 2);
	
	// Scroll the container
	container.scrollTop += pixels;
	
	// Wait the time and scroll further
	setTimeout(function() {
		smoothScroll(element, pixels, count);
	}, time / 20);
}