About window.pageYOffset and document.documentElement.scrollTop_javascript tips

For example:
Css: Assume the following simple settings;
html{height:1000px;}
JS:

Copy code The code is as follows:

function(){
window.scrollBy(0,100);
alert(window.pageYOffset);
}

Results:
//Pop up after clicking once: 100; the result is a numerical value, read-only attribute; value: Integer (integer), default: 0;
Note: When the scroll bar When reaching the bottom of the page, window.pageYOffset=1000-document.documentElement.clientHeight;