如何在 Python 中使 Selenium WebDriver 休眠几毫秒

Question

我time在我的脚本中使用库：

import time
time.sleep(1)

它可以让我的 Selenium WebDriver 休眠一秒钟，但 250 毫秒怎么可能呢？

Answer 1

要将webdriver的执行暂停几毫秒，您可以传递number of seconds或floating point number of seconds如下：

import time
time.sleep(1) #sleep for 1 sec
time.sleep(0.25) #sleep for 250 milliseconds

然而在使用硒和webdriver的用于自动化使用time.sleep(secs)没有任何特定的条件，以实现 失败的目的自动化，应该不惜一切代价避免。根据文档：

time.sleep(secs)在给定的秒数内暂停当前线程的执行。参数可能是一个浮点数，以指示更精确的睡眠时间。实际的暂停时间可能比请求的少，因为任何捕获的信号都会在执行该信号的捕获例程后终止 sleep()。此外，由于系统中其他活动的调度，暂停时间可能比任意数量的请求长。

因此，根据讨论，time.sleep(sec)您应该使用WebDriverWait()in-conjunction withexpected_conditions()来验证元素的状态，并且三个广泛使用的 expected_conditions 如下：

Presence_of_element_located

Presence_of_element_located(locator)定义如下：

class selenium.webdriver.support.expected_conditions.presence_of_element_located(locator)

Parameter : locator - used to find the element returns the WebElement once it is located

Description : An expectation for checking that an element is present on the DOM of a page. This does not necessarily mean that the element is visible or interactable (i.e. clickable). 

visibility_of_element_located

visibility_of_element_located(locator)定义如下：

class selenium.webdriver.support.expected_conditions.visibility_of_element_located(locator)

Parameter : locator -  used to find the element returns the WebElement once it is located and visible

Description : An expectation for checking that an element is present on the DOM of a page and visible. Visibility means that the element is not only displayed but also has a height and width that is greater than 0.

element_to_be_clickable

element_to_be_clickable(locator)定义如下：

class selenium.webdriver.support.expected_conditions.element_to_be_clickable(locator)

Parameter : locator - used to find the element returns the WebElement once it is visible, enabled and interactable (i.e. clickable).

Description : An Expectation for checking an element is visible, enabled and interactable such that you can click it. 

参考

您可以在WebDriverWait not working as expected 中找到详细的讨论