Accordion with scrolltop using Zepto.js

_scrolltop_accordion.js

Zepto(function($){
  var acc = new Accordion();
  acc.init();
});

function Accordion(){
  this.toggle = $('.mod-accordion_heading_toggle');
  this.panel = $('.mod-accordion_panel');
}
Accordion.prototype.init = function(){
  var self = this;
  self.toggle.removeClass('isOpen').addClass('isClose');
  self.panel.removeClass('isOpen').addClass('isClose');
  self.toggle.on('click', $.proxy(self.event, self));
};
Accordion.prototype.event = function(e){
  var self = this;
  e.preventDefault();
  self.slideOpen(e.currentTarget);
  self.transition(e.currentTarget);
};
Accordion.prototype.slideOpen = function(target){
  var self = this;
  if($(target).hasClass('isClose')) {
    $(target).removeClass('isClose').addClass('isOpen');
    $(target).parent().next().removeClass('isClose').addClass('isOpen');
  } else {
    $(target).removeClass('isOpen').addClass('isClose');
    $(target).parent().next().removeClass('isOpen').addClass('isClose');
  }
};
Accordion.prototype.transition = function(target){
	var self = this,
	    position = Math.floor($(target).parent().offset().top),
	    scrollNumber = position;
	self.scroll(scrollNumber, 100);
};
Accordion.prototype.scroll = function(scrollTo, duration){
  var scrollFrom = parseInt(document.body.scrollTop),
      num = 0,
      run = 5,
      timer;
  scrollTo = parseInt(scrollTo);
  duration /= run;
  timer = setInterval(function () {
    i++;
    document.body.scrollTop = (scrollTo - scrollFrom) / duration * num+ scrollFrom;
    if (num >= duration) {
      clearInterval(timer);
    }
  }, run);
};