Dim result As DialogResult = MessageBox.Show("message", "caption", MessageBoxButtons.YesNoCancel)
If result = DialogResult.Cancel Then
    MessageBox.Show("Cancel pressed")
ElseIf result = DialogResult.No Then
    MessageBox.Show("No pressed")
ElseIf result = DialogResult.Yes Then
    MessageBox.Show("Yes pressed")
End If

var proceed = confirm("Are you sure you want to proceed?");
if (proceed) {
  //proceed
} else {
  //don't proceed
}

    if (confirm('Are you sure ?')) {
        console.log('ok');
    }else
    {
      console.log('cancel')
    }