我需要检测用户是否滚动到页面底部。如果它们在页面的底部,当我在底部添加新内容时,我会自动将它们滚动到新的底部。如果他们不在底部,他们正在阅读页面上更高的先前内容,所以我不想自动滚动他们,因为他们想呆在那里。

我如何检测用户是否滚动到页面的底部,或者他们是否在页面上滚动得更高?


当前回答

我一直在寻找答案,但还没有找到确切的答案。这是一个纯javascript解决方案,与最新的Firefox, IE和Chrome在这个答案的时间:

// document.body.scrollTop alone should do the job but that actually works only in case of Chrome.
// With IE and Firefox it also works sometimes (seemingly with very simple pages where you have
// only a <pre> or something like that) but I don't know when. This hack seems to work always.
var scrollTop = (document.documentElement && document.documentElement.scrollTop) || document.body.scrollTop;

// Grodriguez's fix for scrollHeight:
// accounting for cases where html/body are set to height:100%
var scrollHeight = (document.documentElement && document.documentElement.scrollHeight) || document.body.scrollHeight;

// >= is needed because if the horizontal scrollbar is visible then window.innerHeight includes
// it and in that case the left side of the equation is somewhat greater.
var scrolledToBottom = (scrollTop + window.innerHeight) >= scrollHeight;

// As a bonus: how to scroll to the bottom programmatically by keeping the horizontal scrollpos:
// Since window.innerHeight includes the height of the horizontal scrollbar when it is visible
// the correct vertical scrollTop would be
// scrollHeight-window.innerHeight+sizeof(horizontal_scrollbar)
// Since we don't know the visibility/size of the horizontal scrollbar
// we scroll to scrollHeight that exceeds the value of the
// desired scrollTop but it seems to scroll to the bottom with all browsers
// without problems even when the horizontal scrollbar is visible.
var scrollLeft = (document.documentElement && document.documentElement.scrollLeft) || document.body.scrollLeft;
window.scrollTo(scrollLeft, scrollHeight);

其他回答

const handleScroll = () => {
    if (Math.round(window.scrollY + window.innerHeight) >= Math.round(document.body.scrollHeight)) {
        onScroll();
    }
};

这段代码在Firefox和IE中也适用。

新的解决方案。

一个问题是缺少标准的主滚动元素。最近实施的文件。scrollingElement可以用来尝试克服这个问题。下面是一个跨浏览器的解决方案。

function atEnd() {
    var c = [document.scrollingElement.scrollHeight, document.body.scrollHeight, document.body.offsetHeight].sort(function(a,b){return b-a}) // select longest candidate for scrollable length
    return (window.innerHeight + window.scrollY + 2 >= c[0]) // compare with scroll position + some give
}
function scrolling() {
    if (atEnd()) 
        //do something
}
window.addEventListener('scroll', scrolling, {passive: true});
window.onscroll = function(ev) {
    if ((window.innerHeight + window.scrollY) >= document.body.offsetHeight) {
        // you're at the bottom of the page
    }
};

看到演示

我一直在寻找答案,但还没有找到确切的答案。这是一个纯javascript解决方案,与最新的Firefox, IE和Chrome在这个答案的时间:

// document.body.scrollTop alone should do the job but that actually works only in case of Chrome.
// With IE and Firefox it also works sometimes (seemingly with very simple pages where you have
// only a <pre> or something like that) but I don't know when. This hack seems to work always.
var scrollTop = (document.documentElement && document.documentElement.scrollTop) || document.body.scrollTop;

// Grodriguez's fix for scrollHeight:
// accounting for cases where html/body are set to height:100%
var scrollHeight = (document.documentElement && document.documentElement.scrollHeight) || document.body.scrollHeight;

// >= is needed because if the horizontal scrollbar is visible then window.innerHeight includes
// it and in that case the left side of the equation is somewhat greater.
var scrolledToBottom = (scrollTop + window.innerHeight) >= scrollHeight;

// As a bonus: how to scroll to the bottom programmatically by keeping the horizontal scrollpos:
// Since window.innerHeight includes the height of the horizontal scrollbar when it is visible
// the correct vertical scrollTop would be
// scrollHeight-window.innerHeight+sizeof(horizontal_scrollbar)
// Since we don't know the visibility/size of the horizontal scrollbar
// we scroll to scrollHeight that exceeds the value of the
// desired scrollTop but it seems to scroll to the bottom with all browsers
// without problems even when the horizontal scrollbar is visible.
var scrollLeft = (document.documentElement && document.documentElement.scrollLeft) || document.body.scrollLeft;
window.scrollTo(scrollLeft, scrollHeight);

如果你喜欢jquery

$(window).scroll(function() {
  if($(window).scrollTop() + $(window).height() >= $(document).height()) {
    // doSomethingHere();
  }
});