js滑动页面时，平滑过渡，示例

setScrollTopSmooth(end, time?){const start = this.getScrollTop();const val = end-start;const times = time ? time/10 : 30;const step = Math.floor(val/times);if(Math.abs(val)>2){const timer = setInterval(()=>{const nowStart = this.getScrollTop();const nextStart = nowStart + step;if(Math.abs(end-nextStart) < Math.abs(step/2) || (val>0 && nextStart >= end) || (val<0 && nextStart <= end)){clearInterval(timer);this.setScrollTop(end);}else{this.setScrollTop(nextStart);}},10)}}getScrollTop(){//获取scrolltop
}setScrollTop(){//设置scroll
}