How can I make sure if some HTML elements are loaded for Selenium + Python?

Question

From this link, I assume the DOM should be loaded as a whole at first in RAM.

How DOM works/is loaded? (in HTML)

But then I test in Selenium with a timeout e

Answer 1

I found the answer by checking the loading behavior of HTML.

Basically the HTML loads upside down, that said, I just have to check if a elemet behind the elemt, e.g. if another element comes after , just check if another element is presented or not. If yes, then all the elements must be loaded.