Natural scrolling duration

[Harti]

Heya! I really like your skrollr project but I felt there was something amiss (like #9). So I coded it. Unfortunately I'm really awkward at using git so I'll just paste the feature request code here and you can do with it what you want.

What it does is take the current distance between your positionY and the target into account, then calculate an appropriate transition speed. "Appropriate" as in: "don't scroll at ultra lightning speed when scrolling to distant elements; but also don't take ages". This is achieved by sqrt(), and a magic number that felt right (25).

var handleLink = function(link, fake) {
        //Don't use the href property (link.href) because it contains the absolute url.
        var href = link.getAttribute('href');

        //Check if it's a hashlink.
        if(!/^#/.test(href)) {
            return false;
        }

        //Now get the targetTop to scroll to.
        var targetTop;

        //If there's a data-menu-top attribute, it overrides the actuall anchor offset.
        var menuTop = link.getAttribute(MENU_TOP_ATTR);

        if(menuTop !== null) {
            targetTop = +menuTop;
        } else {
            var scrollTarget = document.getElementById(href.substr(1));

            //Ignore the click if no target is found.
            if(!scrollTarget) {
                return false;
            }

            targetTop = _skrollrInstance.relativeToAbsolute(scrollTarget, 'top', 'top');

            var menuOffset = scrollTarget.getAttribute(MENU_OFFSET_ATTR);

            if(menuOffset !== null) {
                targetTop += +menuOffset;
            }


            if(window.pageYOffset) {
                var currentYOffset = pageYOffset;
            } else {
                var currentYOffset = document.body.scrollTop;
            }
            var distanceY = Math.abs(currentYOffset - targetTop),
            naturalDuration = Math.sqrt(distanceY) * 25;

        }

        if(supportsHistory && !fake) {
            history.pushState({top: targetTop}, '', href);
        }

        //Now finally scroll there.
        if(_animate && !fake) {
            _skrollrInstance.animateTo(targetTop, {
                duration: (_duration === "natural" ? naturalDuration : _duration),
                easing: _easing
            });
        } else {
            defer(function() {
                _skrollrInstance.setScrollTop(targetTop);
            });
        }

        return true;
    };

Best regards,

Harti

[Prinzhorn]

Am I right that, if #9 gets included, you can just do these calculations outside of skrollr-menu?