回调函数Angular12和电容V-3中的访问类成员

Question

我使用下面的代码导航到父组件上点击“设备硬件回按钮”。我正在使用电容3.0和设备反向按钮正常工作。实际问题是我无法访问回调函数中的类成员。

下面是代码

  export class ConfirmBoxComponent extends DialogContentBase implements OnInit{
     constructor(public dialog: DialogRef, public myService : MyService) {
        super(dialog);
       
      }
      ngOnInit(): void {
        this.handleHardwareBackButton();
      }
     
      public onCancelAction(): void {
        console.log("Cancel confirmed", this.dialog)
        myService.closeDialog();// closeDialog not available thru arrow or callback functions
      }
    
  handleHardwareBackButton(){
   App.addListener('backButton',function(){
    this.onCancelAction() //not able to access onCancelMethod within callback
   })
  }

    }

问题是，我得到的"this.onCancelAction“不是一种方法。此外，我尝试了下面的代码，但没有用。

handleHardwareBackButton(){
   App.addListener('backButton',function(){
    this.dialog.close({ actionConfirmed : false }); //here this line doesn't get executed. Also no errors observed
   }.bind(this))
  }

我哪里出问题了吗？请指导我如何在回调函数中访问类成员？

Answer 1

试试这样的..。

export class ConfirmBoxComponent extends DialogContentBase implements OnInit {
    constructor(public dialog: DialogRef) {
        super(dialog);

    }
    ngOnInit(): void {
        this.handleHardwareBackButton();
    }

    public onCancelAction(): void {
        console.log("Cancel confirmed", this.dialog)
        this.dialog.close({ actionConfirmed: false });
    }

    handleHardwareBackButton() {
        App.addListener('backButton', () => {
            this.onCancelAction() //not able to access onCancelMethod within callback
        })
    }
}