jQuery: detecting reaching bottom of scroll doesn&

问题:

So basically my problem is a seemingly simple one.

You can see it in action at http://furnace.howcode.com (please note that data is returned via Ajax, so if nothing happens give it a few moments!).

What's MEANT to happen, is in the second column when you reach the bottom of scrolling, the next 5 results are returned.

But what actually happens is it only returns the 5 results when you hit the TOP of the scroll area. Try it: scroll down, nothing happens. Scroll back up to the top, the results are returned.

What's going wrong?

Here's my code I'm using:

$('#col2').scroll(function(){
    if ($('#col2').scrollTop() == $('#col2').height() - $('#col2').height()){
       loadMore();
    }
});

loadMore(); is the function that gets the data and appends it.

So what's going wrong here? Thanks for your help!

回答1:

Your math is wrong, your saying if the scrollbar position is equal to the height of the column minus the height of the column (which equals zero) load more. that's why your loadMore() is called at the top of your col.

Try:

$('#col2').scroll(function(){
    if ($('#col2').scrollTop() == $('#col2').height()){
       loadMore();
    }
});

回答2:

The following has been tested, and works fine:

$(window).scroll(function() {
  if ($(window).scrollTop() == $(document).height() - $(window).height()) {
    loadMore();
  }
});

回答3:

This has worked for me in the past.

var col = $('#col2');
col.scroll(function(){
   if (col.outerHeight() == (col.get(0).scrollHeight - col.scrollTop()))
       loadMore(); 
});

Here's a good explanation too.

回答4:

I found an alternative that works.

None of these answers worked for me (currently testing in FireFox 22.0), and after a lot of research I found, what seems to be, a much cleaner and straight forward solution.

Implemented solution:

function IsScrollbarAtBottom() {
    var documentHeight = $(document).height();
    var scrollDifference = $(window).height() + $(window).scrollTop();
    return (documentHeight == scrollDifference);
}

Resource: http://jquery.10927.n7.nabble.com/How-can-we-find-out-scrollbar-position-has-reached-at-the-bottom-in-js-td145336.html

Regards

回答5:

The solution that jordanstephens posted is on the right track. However, what you need is not the height of #col2, you need the height of the parent element of #col2.

Example:

$('#col2').scroll(function(){
  if ($('#col2').scrollTop() == $('#col2').parent().height()) {
    loadMore();
  }
}

回答6:

Maybe the following will work:

1. HTML - wrap whatever is inside #col2 with another DIV, say #col2-inner
2. CSS - set a fixed height and 'overflow: auto' only for #col2

3. JS - see plugin below:

   $.fn.scrollPaging = function (handler) {
       return this.each(function () {
           var $this = $(this),
               $inner = $this.children().first();
   
           $this.scroll(function (event) {
               var scrollBottom = $this.scrollTop() + $this.height(),
                   totalScroll = $inner.height();
   
               if (scrollBottom >= totalScroll) {
                   handler();
               }
           });
   
       });
   };
   
   $('#col2').scrollPaging(loadMore);
   

回答7:

@munch was closest, but if you have a border on the element, then you need to use .innerHeight() instead of .outerHeight() since the latter includes the border and .scrollTop() does not (.height() is also out if you have padding). Also, at least as of jQuery 1.7.1 and maybe earlier, I'd recommend using .prop('scrollHeight') instead of retrieving it directly from the DOM. I found some talk that the DOM scrollHeight is broken on IE 5-8 and the jQuery function abstracts that for me, at least on IE8.

var $col = $('#col2');
$col.scroll(function(){
if ($col.innerHeight() == $col.prop('scrollHeight') - $col.scrollTop())
    loadMore(); 
});

回答8:

I know this question is already solved, but a concern when using jQuery scrollTOp() function on element other than on $(window).scrollTop() or $(document).scrollTop() since some issue like

jQuery: detecting reaching bottom of scroll doesn't work, only detects the top

Explain why scrollTop() always returns 0 here

$(document).scrollTop() always returns 0

So you can use

$(window).scrollTop() - $('your_selector').offset().top 

instead of

$('your_selector').scrollTOp() 

to avoid the jQuery scrollTOp() issue.

My suggestion is as follows:

   $(window).scroll(function() {
       var $more = $('#col2');
       var top = $(window).scrollTop() - $more.offset().top;
       if(top + $more.innerHeight() >= $more[0].scrollHeight) {
          loadMore();
       }
   });