HarmonyOS 关于子组件调用父组件方法的问题

@Entry  
@Component  
struct Index12 {  
  clickFunc (data:number){  
    console.log(data.toString())  
  
  }  
  
  build() {  
    Row() {  
      Column() {  
        child({click:(data:number):void=>this.clickFunc(data)})  
      }  
      .width('100%')  
    }  
    .height('100%')  
  }  
}  
  
@Component  
export struct child {  
  
  click?=(data:number)=>{};  
  
  
  build() {  
    Row() {  
      Column() {  
        Text('点击子组件')  
          .onClick(()=>{  
            if (this.click != undefined ) {  
              this.click(123);  
            }  
          })  
  
      }  
      .width('100%')  
    }  
    .height('100%')  
  }  
  
}