HarmonyOS使用Web组件如何监听滚动位置

import { webview } from '@kit.ArkWeb' 
@Entry 
@Component 
struct WebPage { 
  controller: webView.WebviewController = new webView.WebviewController(); 
  aaa:number=0 
  build() { 
    Column() { 
      Web({ src: 'https://developer.huawei.com/consumer/cn/', controller: this.controller }) 
        .javaScriptAccess(true) 
        .domStorageAccess(true) 
        .verticalScrollBarAccess(true) 
        .onScroll((event) => { 
          if (event.yOffset>this.aaa){ 
            console.log('aaa下滑') 
          } 
          if (this.aaa>event.yOffset){ 
            console.log('aaa上滑'); 
          } 
          this.aaa=event.yOffset 
        })}}}