用这种方式在app端确实是可以修改节点样式，但是会出现很明显的卡顿

<img ref='dd' class="directory_bg" src="static/image/directory/directory_bg.png" :style="[{marginTop: setTop}]"/>
<scroll-view class="directory_list" scroll-y @scroll='soll'>
			<view class="" v-for="(item,index) in 30" :key="index" style="height: 100px;">
				{{item}}--{{index}}
			</view>
		</scroll-view>
		
data(){
        return {
			imgH:100,
			setTop:0
        }  
    },
    
//这个是 scroll-view组件的 @scroll的事件监听
soll(event){
	// console.log(this.$refs.dd.offsetHeight)
	event.preventDefault()
	const {scrollHeight, deltaY, scrollTop} = event.detail;
	
	let view = uni.createSelectorQuery().selectAll('.directory_bg');
	this.setTop = -((scrollTop / this.imgH) * 34) +'px';
}

感谢原作者的提醒：https://blog.csdn.net/qqpaowenquan/article/details/109329318