from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
driver = webdriver.Firefox()
driver.get("http://somedomain/url_that_delays_loading")
try:
element = WebDriverWait(driver, 10).until( //使用 WebDriverWait()来等待 最多等10秒来等待找到指定条件的元素， 超时未找到抛出TimeoutException
EC.presence_of_element_located((By.ID, "myDynamicElement"))
)
finally:
driver.quit()
其他的EC方法 用于自动化浏览器
title_is title_contains presence_of_element_located visibility_of_element_located visibility_of presence_of_all_elements_located text_to_be_present_in_element text_to_be_present_in_element_value frame_to_be_available_and_switch_to_it invisibility_of_element_located element_to_be_clickable staleness_of element_to_be_selected element_located_to_be_selected element_selection_state_to_be element_located_selection_state_to_be alert_is_present
例如：
from selenium.webdriver.support import expected_conditions as EC wait = WebDriverWait(driver, 10) element = wait.until(EC.element_to_be_clickable((By.ID, 'someid')))
也可创建自定义等待条件。可以使用带有__call__方法的类创建自定义等待条件，当条件不匹配时，该方法将返回False。
1 class element_has_css_class(object): //自定义的方法
2 """An expectation for checking that an element has a particular css class.
3
4 locator - used to find the element
5 returns the WebElement once it has the particular css class
6 """
7 def __init__(self, locator, css_class):
8 self.locator = locator
9 self.css_class = css_class
10
11 def __call__(self, driver):
12 element = driver.find_element(*self.locator) # Finding the referenced element
13 if self.css_class in element.get_attribute("class"):
14 return element
15 else:
16 return False
17
18 # Wait until an element with id='myNewInput' has class 'myCSSClass'
19 wait = WebDriverWait(driver, 10)
20 element = wait.until(element_has_css_class((By.ID, 'myNewInput'), "myCSSClass")) // 先通过 init方法 call 方法
3.默认等待
1 from selenium import webdriver
2
3 driver = webdriver.Firefox()
4 driver.implicitly_wait(10) # seconds
5 driver.get("http://somedomain/url_that_delays_loading")
6 myDynamicElement = driver.find_element_by_id("myDynamicElement")
标签：webdriver,selenium,driver,page,objects,element,class,css From： https://www.cnblogs.com/shaitaiyang/p/16778301.html