Pop window instance (document) pops up on the page. The difference between the height () and the (window) height ()

jquery (window). Height () represents the size of the currently visible area, while jquery (document). Height () represents the height of the entire document and is used in a specific case.

Note jquery (window) when the size of the browser window changes (such as when you maximize or pull large windows). Height () is changed, but jquery (document). Height () is constant.

$ (document). ScrollTop () Gets the distance from the vertical scroll of the  top of the window to the top of the page where it is currently 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 the bottom as long as you get ScrollTop () >=$ (document). Height ()-$ (window). Height ()  You know you're rolling to the end.

$ (document). Height ()  //To get the entire page
$ (window). Height ()  //is the size of the portion of the page that is currently visible to your browser, which is different from the  document when you zoom in on the browser window size  . It should be understood in English.


$ (document). Scroll (function () {
    $ ("#lb"). Text ($ (document). ScrollTop ());
})
<span id= "lb" style= "top:100px;left:100px;position:fixed;" ></span><!--a fixed span tag for easy viewing when scrolling