javascript - The JQuery window object scroll top function -

javascript - The JQuery window object scroll top function -

i started learning javascript , jquery, , have question regarding window object $(window). have code, create div stick top of screen when scrolled top.

$(function () { $(window).scroll(function(){ var window_top = $(window).scrolltop(); var div_top = $("#sticky-anchor").offset().top; if (window_top > div_top) { $('#sticky').addclass('stick'); } else { $('#sticky').removeclass('stick'); } }); });

what don't understand if entire screen window, when window_top > div_top?

the top property returns topmost browser window of current window.

top useful both when you're dealing frames , when dealing windows have been opened other pages.

the place in reddish considered top! if scroll page, whichever part of page in red area, part @ window.top.

so, if div above top, window_top > div_top returns true otherwise else part gets executed!

javascript jquery