在dart中抓取web时，如何获取href属性的值？

import 'package:http/http.dart' as http;
import 'package:html/parser.dart' as parser;
import 'package:html/dom.dart';

var response = await http.get(Uri.parse('https://example.com'));
var document = parser.parse(response.body);

var elements = document.querySelectorAll('[href]');

for (var element in elements) {
  var href = element.attributes['href'];
  print(href);
}