window.onscroll=function(){
            var title = document.getElementById("div");//獲取到導航欄id
            //使用JS原生物件，獲取元素的Class樣式列表
            var titleClientRect = title.getBoundingClientRect();
            if((titleClientRect.top - titleClientRect.height) < 0) {
                console.log("hide")
            } else {
                console.log("show")
            }
             }
 

      var element = document.getElementById(msg); //頁面滾動功能
      element.scrollIntoView({
        behavior: "smooth"
      });