Check if a user has scrolled to the bottom [duplicate]

Question

I'm making a pagination system (sort of like Facebook) where the content loads when the user scrolls to the bottom. I imagine the best way to do that is to find when the user is at the bottom of the page and run an Ajax query to load more posts.

The only problem is I don't know how to check if the user has scrolled to the bottom of the page. Any ideas?

I'm using jQuery, so feel free to provide answers that use it.

Answer 1

I'm not exactly sure why this has not been posted yet, but as per the documentation from MDN, the simplest way is by using native javascript properties:

element.scrollHeight - element.scrollTop === element.clientHeight 

Returns true when you're at the bottom of any scrollable element. So simply using javascript:

element.addEventListener('scroll', function(event) {     var element = event.target;     if (element.scrollHeight - element.scrollTop === element.clientHeight)     {         console.log('scrolled');     } }); 

scrollHeight have wide support in browsers, from ie 8 to be more precise, while clientHeight and scrollTop are both supported by everyone. Even ie 6. This should be cross browser safe.

Answer 2

Use the .scroll() event on window, like this:

$(window).scroll(function() {    if($(window).scrollTop() + $(window).height() == $(document).height()) {        alert("bottom!");    } }); 

You can test it here, this takes the top scroll of the window, so how much it's scrolled down, adds the height of the visible window and checks if that equals the height of the overall content (document). If you wanted to instead check if the user is near the bottom, it'd look something like this:

$(window).scroll(function() {    if($(window).scrollTop() + $(window).height() > $(document).height() - 100) {        alert("near bottom!");    } }); 

You can test that version here, just adjust that 100 to whatever pixel from the bottom you want to trigger on.