Back to top effects

Here's what you've learned recently to get back to top effects:

<input id= "btn1" type= "button" value= "Back to Top"/>

#btn1 {position:fixed;bottom:10px;right:10px;}

Window.onload=funcition () {    var obtn=document.getelementbyid ("btn");     var timer=null;    //declare a variable to see if the system or the user scrolls     var  Sbys=true;    window.onscroll=funcition () {         if (!sbys) {            clearinterval (timer);         }        sBys=false;     }    obtn.onclick=funcition () {        Timer = setinterval (Funcition () {             //Get scrolltop            var scrolltop= document.documentelement.scrolltop| | Document.body.scrolltop;            //calculates the buffer speed when the button is clicked back to the top             var ispeed= Math.floor (-SCROLLTOP/8);             if (scrollTop= =0) {                 Clearinterval (timer)             }             sBys=true;             document.documentelement.scrolltop=document.body.scrolltop=scrolltop+ ispeed;        },30)     }}

Knowledge Points: 1. Calculate speed (buffer) down rounding

2. Need to clear the timer when scrolltop==0

3. Need to determine whether the user or JS operation scroll bar, if the user action to clear the timer

Back to top effects