jquery: $(window).scrollTop() but no $(window).scrollBottom()

I want to place an element to the bottom of the page whenever the user scrolls the page. It's like "fixed position" but I can't use "position: fixed" css as many of my clients' browser can't support that.

I noticed jquery can get current viewport's top position, but how can I get the bottom of the scroll viewport?

So I am asking how to know: $(window).scrollBottom()

Solution 1:

var scrollBottom = $(window).scrollTop() + $(window).height();

Solution 2:

I would say that a scrollBottom as a direct opposite of scrollTop should be:

var scrollBottom = $(document).height() - $(window).height() - $(window).scrollTop();

Here is a small ugly test that works for me:

// SCROLLTESTER START //
$('<h1 id="st" style="position: fixed; right: 25px; bottom: 25px;"></h1>').insertAfter('body');

$(window).scroll(function () {
  var st = $(window).scrollTop();
  var scrollBottom = $(document).height() - $(window).height() - $(window).scrollTop();

  $('#st').replaceWith('<h1 id="st" style="position: fixed; right: 25px; bottom: 25px;">scrollTop: ' + st + '<br>scrollBottom: ' + scrollBottom + '</h1>');
});
// SCROLLTESTER END //

Solution 3:

For the future, I've made scrollBottom into a jquery plugin, usable in the same way that scrollTop is (i.e. you can set a number and it will scroll that amount from the bottom of the page and return the number of pixels from the bottom of the page, or, return the number of pixels from the bottom of the page if no number is provided)

$.fn.scrollBottom = function(scroll){
  if(typeof scroll === 'number'){
    window.scrollTo(0,$(document).height() - $(window).height() - scroll);
    return $(document).height() - $(window).height() - scroll;
  } else {
    return $(document).height() - $(window).height() - $(window).scrollTop();
  }
}
//Basic Usage
$(window).scrollBottom(500);

Solution 4:

var scrollBottom =
    $(document).height() - $(window).height() - $(window).scrollTop();

I think it is better to get bottom scroll.

Solution 5:

This will scroll to the very top:

$(window).animate({scrollTop: 0});

This will scroll to the very bottom:

$(window).animate({scrollTop: $(document).height() + $(window).height()});

.. change window to your desired container id or class if necessary (in quotes).