如何实现对LocalStorage的实时监听？

let para: Record<string, number> = { 'PropA': 47 };
let storage: LocalStorage = new LocalStorage(para);
@Entry(storage)
@Component
struct Index {
   build() {
      Column() {
        Button("CLick").onClick(() => {//点击按钮改变PropA的值
          storage.set("PropA", 60)
        })
        Child()
      }.height("100%")
      .alignItems(HorizontalAlign.Center)
      .justifyContent(FlexAlign.Center)
}
}
@Component
export struct Child {
  @LocalStorageProp("PropA") @Watch("onChange") aa: number = 0
  onChange() {
    console.log("===========PropA:发生了变化")
  }
}