WebDriver提供了兩種型別的等待：顯示等待和隱式等待。

1.顯示等待使WebDriver等待某個條件成立時繼續執行，否則在達到最大時長時丟擲超時異常（TimeoutException）。

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.Chrome()
driver.get("http://www.baidu.com")

#WedDriverWait 顯式等待
element =WebDriverWait(driver,5,0.5).until(
    EC.presence_of_element_located((By.ID,"kw22"))
    )
element.send_keys('selenium')

driver.quit()
 

from selenium import webdriver
from time import sleep,ctime

driver=webdriver.Firefox()
driver.get("http://www.baidu.com")

print(ctime())
for i in range(10):
    try:
        el = driver.find_element_by_id("kw22")
        if el.is_displayed():            
            break
    except:
        pass
    sleep(1)
else:
    print("time out")

print(ctime())
driver.close()