Webdriver (python)中调用JS

1、Webdriver 中调用JS，由于页面中的input是被隐藏起来的，所以必须用JS把隐藏的元素显示出来；

browser.find_element_by_xpath("//div[@id='surveyItemsWrap']/div/div[2]/button[2]").click()
time.sleep(5)
inputs=browser.find_element_by_xpath("//body/input")
js="var q=document.getElementByClassName('ts_bg alert');q.style.display='block';"
# setAttribute(\"style\",\"display:block\
print "js"
browser.execute_script(js)
browser.find_element_by_xpath("//body/input").send_keys('F:\\Img\2.jpg')
print "ok"

报错：

Traceback (most recent call last):
File "E:\eclipse\PythonCase\src\Survey_test\LogicMore.py", line 85, in test_Surveyor
browser.execute_script(js)
File "D:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 396, in execute_script
{'script': script, 'args':converted_args})['value']
File "D:\Python27\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 164, in execute
self.error_handler.check_response(response)
File "D:\Python27\lib\site-packages\selenium\webdriver\remote\errorhandler.py", line 164, in check_response
raise exception_class(message, screen, stacktrace)
WebDriverException: Message: u"unknown error: Object #<HTMLDocument> has no method 'getElementByClassName'\n  (Session info: chrome=28.0.1500.72)\n  (Driver info: chromedriver=2.3,platform=Windows NT 6.1 SP1 x86_64)"

PS: JS有待加深学习！