I have a selenium script (python) that clicks a reply button to make the class anonemail appear. The time it takes for the class anonemail to appear varies. Because of that
As per the best practices:
If your usecase is to validate the presence of any element you need to induce WebDriverWait setting the expected_conditions as presence_of_element_located() which is the expectation for checking that an element is present on the DOM of a page. This does not necessarily mean that the element is visible. So the effective line of code will be:
WebDriverWait(browser, 20).until(EC.presence_of_element_located((By.CSS_SELECTOR, ".reply-button"))).click()
If your usecase is to extract any attribute of any element you need to induce WebDriverWait setting the expected_conditions as visibility_of_element_located(locator) which is 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. So in your usecase effectively the line of code will be:
email = WebDriverWait(driver, 20).until(EC.visibility_of_element_located((By.CSS_SELECTOR, "element_css"))).get_attribute("value")
If your usecase is to invoke click()
on any element you need to induce WebDriverWait setting the expected_conditions as element_to_be_clickable() which is an expectation for for checking an element is visible and enabled such that you can click it. So in your usecase effectively the line of code will be:
WebDriverWait(browser, 20).until(EC.element_to_be_clickable((By.CSS_SELECTOR, ".reply-button"))).click()
You can find a couple of detailed discussion in: