js滚动到从顶部动画

js

scrollToptimer = setInterval(function () {
    console.log("定时循环回到顶部")
    var top = document.body.scrollTop || document.documentElement.scrollTop;
    var speed = top / 4;
    if (document.body.scrollTop!=0) {
        document.body.scrollTop -= speed;
    }else {
        document.documentElement.scrollTop -= speed;
    }
    if (top == 0) {
        clearInterval(scrollToptimer);
    }
}, 30); 

jquery

$("html,body").animate({scrollTop:0});