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  var scrollElm = (function() {
    if('scrollingElement' in document) return document.scrollingElement;
    if(navigator.userAgent.indexOf('WebKit') != -1) return document.body;
    return document.documentElement;
  })();

  var duration = 500;
  var ignore = '.noscroll';
  var easing = function (t, b, c, d) { return c * (0.5 - Math.cos(t / d * Math.PI) / 2) + b; }; //jswing
  var smoothScrollElm = [].slice.call(document.querySelectorAll('.hoge'));

  Array.prototype.forEach.call(smoothScrollElm, function(elm) {
    elm.addEventListener('click', function(e) {
      e.preventDefault();
      var targetElm = document.querySelector('body');
      if(!targetElm) return;
      var targetPos = targetElm.getBoundingClientRect().top;
      var startTime = Date.now();
      var scrollFrom = scrollElm.scrollTop;
      (function loop() {
        var currentTime = Date.now() - startTime;
        if(currentTime < duration) {
          scrollTo(0, easing(currentTime, scrollFrom, targetPos, duration));
          window.requestAnimationFrame(loop);
        } else {
          scrollTo(0, targetPos + scrollFrom);
        }
      })();
    })
  });

$('a[href^="#"]').click(function() {
  var speed = 400;
  var href= $(this).attr("href");
  var target = $(href == "#" || href == "" ? 'html' : href);
  var position = target.offset().top;
  $('body,html').animate({scrollTop:position}, speed, 'swing');
  return false;
});