如何获取是否登陆成功或者失败啊?

procedure TForm1.btnloginClick(Sender: TObject);
var
Doc: IHTMLDocument2;
userinputelement, pwdinputelement: ihtmlinputelement;
begin
doc := wb1.document as ihtmldocument2;
userinputelement := (doc.all.item('username', 0) as ihtmlinputelement);
userinputelement.value := Trim(edt1.Text);
pwdinputelement := (doc.all.item('userpass', 0) as ihtmlinputelement);
pwdinputelement.value := Trim(edt2.Text);
wb1.OleObject.document.getElementByID('imageField').click ;

end;