ScrollTo With Checks

scrollTo.js

//
// --------------------------------------------------------------------------
// To Top Function
// --------------------------------------------------------------------------
//
function toTop(elementClass) {
  var chapterToTop = $(elementClass).offset();
  chapterToTop = Math.round(chapterToTop.top);

  var windowScrollPosition = $(document).scrollTop();
  windowScrollPosition = windowScrollPosition + 120;

  var page = $("html, body");

  if (windowScrollPosition !== chapterToTop) {
    page.on("scroll mousedown wheel DOMMouseScroll mousewheel keyup touchmove", function(){
      page.stop();
    });
    page.animate({ scrollTop: $(elementClass).offset().top - 120 }, 2000, function(){
      page.off("scroll mousedown wheel DOMMouseScroll mousewheel keyup touchmove");
    });
  }
};