scroll up - js activation

/*----------------------------
     scrollUp
    ---------------------------- */
    $.scrollUp({
        scrollText: '<i class="fa fa-arrow-up" aria-hidden="true"></i>',
        easingType: 'linear',
        scrollSpeed: 900,
        animation: 'fade'
    });

scroll up css

#scrollUp {
  background: #232323 none repeat scroll 0 0;
  border: 1px solid #00b0ff;
  border-radius: 0;
  bottom: 35px;
  box-shadow: 0 0 20px rgba(255, 255, 255, 0) inset;
  color: white;
  cursor: pointer;
  display: none;
  font-size: 17px;
  height: 40px;
  line-height: 20px;
  outline-color: rgba(255, 255, 255, 0.5);
  outline-offset: 0;
  padding-top: 10px;
  position: fixed;
  right: 20px;
  text-align: center;
  text-shadow: none;
  -webkit-transition: all 1250ms cubic-bezier(0.19, 1, 0.22, 1) 0s;
  -o-transition: all 1250ms cubic-bezier(0.19, 1, 0.22, 1) 0s;
  transition: all 1250ms cubic-bezier(0.19, 1, 0.22, 1) 0s;
  width: 40px;
  z-index: 9999;
}

#scrollUp:hover {
  background: #00b0ff none repeat scroll 0 0;
  box-shadow: 0 0 20px rgba(255, 255, 255, 0.5) inset, 0 0 20px rgba(255, 255, 255, 0.2);
  color: white;
  outline: 1px solid rgba(255, 255, 255, 0);
  outline-offset: 15px;
}