SmoothScroll Optimize the code

[nenge123]

simple to replace SmoothScroll

    
    let docbody = document.body,
        dochtml = document.documentElement;
    let $ = s=>document.querySelector(s),
        on = (o,...a)=>o && Reflect.apply(addEventListener, o, a);
    function scrollTo(pos){
    let maxTop = dochtml.offsetHeight - window.innerHeight;
    if(pos>maxTop)pos = maxTop;
    if(pos==dochtml.scrollTop) return;
    let keyframes = [
        { 'marginTop': (pos-dochtml.scrollTop)+'px' },//from
        { 'marginTop': 0+"px" },//to
    ];
    let options = {
            //delay:300,// ms0
            //endDelay// 动ms
            easing:"ease-out",// linear,ease-in
            duration: 800,//ms
            iterations: 1,//
    };
    let _Animation = docbody.animate(keyframes,options);
    dochtml.scrollTop=pos;
    on(_Animation,'finish',e=>{
        //doing callback
    },{once:true, passive: false});
}
document.querySelectorAll('a[href*="#"]').forEach(elm=>on(elm,'click',function(e){
    let href = this.getAttribute('href');
    if($(href)){
        scrollTo($(href).getBoundingClientRect().y-50);
        e.preventDefault();
        e.stopPropagation();
    }
}))

[iBug]

Duplicate of #4247.