How to monitor web's element is changed or not?

Question

So I want to buy discounted stuff online,and the websites will let users buy it at certain time with limited amount , so I use selenium to write an automatic program. and here's a part of my code

while 1:
    start = time.clock()
    try:
        browser.find_element_by_class_name('SasCheckoutButton__mod___1BK9F.CheckoutBar__buyNowBtn___qgDtR.CheckoutBar__checkoutButton___jSkkJ').click()
        print ('located')
        end=time.clock()
        break
    except:
        print("not yet!")

My first idea is to use while to monitor if the button shows up yet ,so that if the button is updated by the website's manager I can press it as soon as possible . but here's the problem , if the web is updated,I don't think I can press it without refreshing , right?(I actually don't know how the engineer manage the web pages , I just guessing based on my experience) so I have to add refreshing in the while , but I think this will slow down the program a lot , so I am wondering if there's any way in selenium to monitor the changing without refreshing? or maybe a more efficient way to add refreshing in the while? because I don't think refreshing every time it can't find the buy button is a good idea.

Does this solves your problem ? : https://stackoverflow.com/questions/26566799/wait-until-page-is-loaded-with-selenium-webdriver-for-python#answer-26567563 — tgrandje, Nov 22 '20 at 12:07
I actually don't have the method to test if WebDriverWait() function is useful or not ,but I wonder that whether it needs refreshing to monitor the changing set by the engineer or not , if it does not , then I think it will work — chungchung, Nov 23 '20 at 05:31

score 1 · Accepted Answer · edited Jan 03 '23 at 07:54

What you can do to monitor how the whole thing works would something like this :

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

browser = ...
url = "..."
delay = 3 # seconds
classname = 'SasCheckoutButton__mod___1BK9F.CheckoutBar__buyNowBtn___qgDtR.CheckoutBar__checkoutButton___jSkkJ'

counter = 0
while True:
    counter += 1
    try:
        browser.get(url)
        if counter >= 10:
            break
        myElem = WebDriverWait(browser, delay).until(EC.presence_of_element_located((By.CLASS_NAME, classname)))
        print ('located')
        break
    except TimeoutException:
        print(f"reload #{counter}")

myElem.click()

Then you could check if you really need to refresh the webpage or if the page "self refreshes" (using something like scripts for example).

How to monitor web's element is changed or not?

1 Answers1