Stop the Scroll in Dynamic Page with Selenium in P

问题:

Hello everyone i'm trying to use selenium and scrapy to scraping some information from https://answers.yahoo.com/dir/index/discover?sid=396545663

I try different method, i use Selenium and setting PhantomJs like driver. For scrolling down the page, it's a infinite scroll page, i use this instruction:

elem.send_keys(Keys.PAGE_DOWN)

For simulating the press of Page Down button, instead of the JavaScript function:

browser.execute_script("window.scrollTo(0, document.body.scrollHeight);")

Because this one "seems" load less elements in the page.

The main problem is how i can know when i have reached the bottom of the page? Is "Infinite Scroll" page so i can't know when it end i need to scroll down, but i don't have any element in the bottom to analyze.

Actually i use temporized cycle, but look really stupid.

Thanks

回答1:

I would actually look for that "Loading..." indicator. Wait for it to be visible on every scroll, but if you'll get a TimeoutException - there was no loading indicator this time and there are no more items to load.

Sample implementation:

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

wait = WebDriverWait(driver, 10)

while True:
    # do the scrolling
    browser.execute_script("window.scrollTo(0, document.body.scrollHeight);")

    try:
        wait.until(EC.visibility_of_element_located((By.XPATH, "//*[. = 'Loading...']")))
    except TimeoutException:
        break  # not more posts were loaded - exit the loop

Not tested.

回答2:

As example you can create some parallel thread witch will check page for ajax requests. If time between requests is more often than 10 seconds -- you on the end of page. Have no other idea.