python - 有什么方法可以告诉 selenium 在某个时候不要执行 js？

Question

我想抓取一个包含一些由 js 生成的内容的网站。 该站点每 5 秒运行一次 js 更新内容(请求一个新的加密 js 文件，无法解析)。

我的代码:

from selenium import webdriver

driver = webdriver.PhantomJS()
driver.set_window_size(1120, 550)

driver.get(url)

trs = driver.find_elements_by_css_selector('.table tbody tr')

print len(trs)

for tr in trs:
    try:
        items.append(tr.text)
    except:
        # because the js update content, so this tr is missing
        pass

print len(items)

len(items) 与 len(trs) 不匹配。 如何告诉 selenium 在我运行 trs = driver.find_elements_by_css_selector('.table tbody tr') 后停止执行 js 或停止工作？

后面需要用到trs，所以不能用driver.quit()

异常详情:

---------------------------------------------------------------------------
StaleElementReferenceException            Traceback (most recent call last)
<ipython-input-84-b80e3579efca> in <module>()
     11 items = []
     12 for tr in trs:
---> 13     items.append(tr.text)
     14     #items.append(map_label(hidemyass_label, tr.find_elements_by_tag_name('td')))
     15 

C:\Python27\lib\site-packages\selenium\webdriver\remote\webelement.pyc in text(self)
     69     def text(self):
     70         """The text of the element."""
---> 71         return self._execute(Command.GET_ELEMENT_TEXT)['value']
     72 
     73     def click(self):

C:\Python27\lib\site-packages\selenium\webdriver\remote\webelement.pyc in _execute(self, command, params)
    452             params = {}
    453         params['id'] = self._id
--> 454         return self._parent.execute(command, params)
    455 
    456     def find_element(self, by=By.ID, value=None):

C:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.pyc in execute(self, driver_command, params)
    199         response = self.command_executor.execute(driver_command, params)
    200         if response:
--> 201             self.error_handler.check_response(response)
    202             response['value'] = self._unwrap_value(
    203                 response.get('value', None))

C:\Python27\lib\site-packages\selenium\webdriver\remote\errorhandler.pyc in check_response(self, response)
    179         elif exception_class == UnexpectedAlertPresentException and 'alert' in value:
    180             raise exception_class(message, screen, stacktrace, value['alert'].get('text'))
--> 181         raise exception_class(message, screen, stacktrace)
    182 
    183     def _value_or_default(self, obj, key, default):

StaleElementReferenceException: Message: {"errorMessage":"Element is no longer attached to the DOM","request":{"headers":{"Accept":"application/json","Accept-Encoding":"identity","Connection":"close","Content-Type":"application/json;charset=UTF-8","Host":"127.0.0.1:63305","User-Agent":"Python-urllib/2.7"},"httpVersion":"1.1","method":"GET","url":"/text","urlParsed":{"anchor":"","query":"","file":"text","directory":"/","path":"/text","relative":"/text","port":"","host":"","password":"","user":"","userInfo":"","authority":"","protocol":"","source":"/text","queryKey":{},"chunks":["text"]},"urlOriginal":"/session/4bb16340-a3b6-11e5-8ce5-9d0be40203a6/element/%3Awdc%3A1450243990539/text"}}
Screenshot: available via screen

显然 tr 不见了。

PS:我需要使用 Selenium 来选择元素。其他库如 lxml ， pyquery 不知道哪个元素是 display:none 或不是， .text() 经常在 <script> 中得到评论或其他东西，等等错误。遗憾的是 python 没有 Jquery 的完美克隆。

Answer 1

使用抓取。确定页面已加载后，使用以下方法获取正文:

response = TextResponse(url=self.driver.current_url, body=self.driver.page_source, encoding='utf-8')

您现在拥有该页面的静态副本，这样您就可以使用 scrapy 的 response.xpath 来提取您需要的任何数据。这answer更多细节。