selenium determination pulled down box bottommost

Each pull-down document.body.scrollHeight browser interface parameters are changed, when the bottommost Selenium pulled parameter will not be changed, in order to determine whether it is the very bottom, as follows:

def pulldown():
    t = True
    i = 1
    while t:
        check_height = browser.execute_script("return document.body.scrollHeight;")
        for r in range(20):
            t = random.uniform(1, 2)
            time.sleep(t)
            browser.execute_script("window.scrollBy(0,1000)")
            print('第%s页' % str(i))
            i += 1
        check_height1 = browser.execute_script("return document.body.scrollHeight;")
        print(str(check_height)+'**************'+str(check_height1))
        if check_height == check_height1:
            t = False
pulldown()

selenium python3 code is as follows:

from selenium import webdriver
from selenium.webdriver.chrome.options import Options
import time
import random
path = r'E:\chromedriver.exe'
chrome_options = Options() #创建配置对象
chrome_options.add_argument('--headless')
chrome_options.add_argument('--disable-gpu')
chrome_options.add_argument("user-agent='Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36'")
browser = webdriver.Chrome(executable_path=path,chrome_options=chrome_options)