硒-等待，直到元素出现，可见和可交互

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You can use waits. Check for more information in Selenium waits.

In the example below we are waiting 10 seconds for the element to be visible, using the function visibility_of_element_located.

driver = webdriver.Firefox()
driver.get("http://somedomain/url_that_delays_loading")
try:
element = WebDriverWait(driver, 10).until(
EC.visibility_of_element_located((By.ID, "myDynamicElement"))
)
finally:
driver.quit()

小开

You can use implicitly_wait:

from selenium import webdriver


driver = webdriver.Firefox()
driver.implicitly_wait(15)
driver.get("http://url")
driver.find_element_by_id("id_of_element").click()

It waits until element is loaded.

In your case the implementation would be,

browser.implicitly_wait(10)
browser.find_element_by_css_selector(".reply-button").click()
email = browser.find_element_by_css_selector(".anonemail").get_attribute("value")

小开

As per the best practices:

If your use case 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 use case 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 it also has a height and width that is greater than 0. So in your use case, 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 use case 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 checking an element is visible and enabled such that you can click it. So in your use case, effectively the line of code will be:
```
  WebDriverWait(browser, 20).until(EC.element_to_be_clickable((By.CSS_SELECTOR, ".reply-button"))).click()
```

References

You can find a couple of detailed discussion in:

小开

After clicking the Reply button, use .visibility_of_element_located like below:

browser.find_element_by_css_selector(".reply-button").click()


# Wait for initialize, in seconds
wait = WebDriverWait(browser, 10)


email = wait.until(EC.visibility_of_element_located((By.CSS_SELECTOR, '.anonemail'))).get_attribute("value")
print(email)

Following import:

from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

Waits documentation

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I also had a similar problem to yours. I tried using implicit_wait() and WebDriverWait, but they did not work.

So I solved setting the implicit_wait(10) in the web driver instance and using this snippet to click on the button:

element = driver.find_elements_by_xpath("//button[contains(string(), 'Log In')]")[0]
driver.execute_script("arguments[0].click();", element)

小开

WebDriverWait(driver, 5).until( EC.presence_of_element_located((By.CSS_SELECTOR, ".reply-button"))):
- Hey driver, wait (0-5 seconds), when you see .reply-button is presence, return that button to me!
  - presence is present on the DOM. Hidden element is good enough.
WebDriverWait(driver, 5).until( EC.visibility_of_element_located((By.CSS_SELECTOR, ".reply-button”)))):
- Hey driver, wait (0-5 seconds), when you see .reply-button is visibility, return that button to me!
  - visibility is present and visible on the DOM. Hidden element is not good enough!
WebDriverWait(driver, 5).until( EC.element_to_be_clickable((By.CSS_SELECTOR, ".reply-button”)))):
- Hey driver, wait (0-5 seconds), when you see .reply-button is clickable, return that button to me!
  - clickable is present and visible and clickable on the DOM. Hidden element or non-clickable is not good enough!