$ (document). Height and $ (window). Height difference

$ (document). ScrollTop () Gets the distance from the vertical scroll (that is, the distance from the top of the window to the top of the page where the current scroll is scrolled)
$ (document). ScrollLeft () This is the distance to get the horizontal scroll bar

To get the top only need to get to scrolltop () ==0 is the top of the

To get to the bottom, just get scrolltop () >=$ (document). Height ()-$ (window). Height ()
You'll know it's rolling to the end.

Note: $(window). Height () and $ (document) The difference between height ()

JQuery (window). Height () represents the size of the current visible area,
JQuery (document). Height () represents the entire length of the documentation, which can be used in a specific case.

Note: When the size of the browser window changes (such as maximizing or pulling a large window),
JQuery (window). Height () changes, but
JQuery (document). Height () is constant.

$ (document). Height and $ (window). Height difference