我带着更多的Protractor Q& A回来了.所以,我在尝试查找幻灯片菜单中的元素时遇到了一个问题.

html片段：

以下是我尝试从此菜单中获取按钮的方法：

element(by.css('Button[ng-click="logoff()"]'));
element(by.xpath('/html/body/section/div[@class="ng-scope"]/nav[@class="menu slide-menu-left ng-scope"]/md-content/button[@ng-click="logoff()"]'));

量角器不喜欢并继续告诉我这个：

Stacktrace:
  ElementNotVisibleError: element not visible
  (Session info: chrome=40.0.2214.115)
  (Driver info: chromedriver=2.14.313457 (3d645c400edf2e2c500566c9aa096063e707c9cf),platform=Windows NT 6.3 x86_64) (WARNING: The server did not provide any stacktrace information)
Command duration or timeout: 31 milliseconds
Build info: version: '2.45.0', revision: '5017cb8', time: '2015-02-26 23:59:50'

任何人都可以向我提出我可能做错的建议吗？