Snap.svg plug - Animate along path

snap.animAlongPath.js

Snap.plugin(function (Snap, Element, Paper, glob, Fragment) {
  var elproto = Element.prototype;
  elproto.animateAlongPath = function (path, el, start, duration, easing) {
    var callback = this;
    el.transform('t0,0');
    var len = Snap.path.getTotalLength(path), 
        elBB = el.getBBox(),
        elCenter = {
          x: elBB.x + (elBB.width / 2),
          y: elBB.y + (elBB.height / 2),
        };

      Snap
        .animate(start, len, function (value) {
        var movePoint = Snap.path.getPointAtLength(path, value);
        el.transform('t'+ (movePoint.x - elCenter.x) + ',' + (movePoint.y - elCenter.y));
      }, duration, easing, function(){
        callback.animateAlongPath(path, el, start, duration, easing);
      });
  };
});