javascript - 如何找到div的真正底部？

Question

codepen您需要调整 codepen 的大小，以便显示滚动条。我说的是内容内部的内部滚动。

我想知道滚动条是否在 div 的底部。我已经看到这个页面完成了。当我滚动到 div 的底部时，scrollTop 显示 95，而 scrollHeight 显示 210。如何找到真正的底部？

var scroller = $('.fill-area-content');

var getHeight = function() {
  //console.log(scroller.scrollTop());
  console.log('IsAtBottom: ', isAtBottom(scroller));
}

var isAtBottom = function(scroller) {
  var atBottom = false;
  var asRawDom = scroller.get(0);

  console.log('scroll height', asRawDom.scrollHeight);
  console.log(asRawDom.scrollTop);
  //scrollHeight is 210 while Bottom is 95
  //How do I determine true bottom?

  return atBottom;
}

//Stuff I've messed with
/*
console.log(scroller.height());
  console.log($(document).height());
  console.log($(window).height());
  var testHeight = $(document).height() -      $(window).height();
  console.log(testHeight);
*/

<input type="button" onclick="getHeight()" value="Get Height"/>
<div class="flexbox-container">
    <div class="flexbox-item header">
        Header
    </div>

    <div class="flexbox-item flexbox-inner-container flexbox-item-grow">
        <div class="flexbox-item-grow fill-area-content">
          Content
            <br /><br />
            Emulates height 100% with a horizontal flexbox with stretch
            <br /><br />      
            This box with a border should fill the blue area except for the padding (just to show the middle flexbox item).  Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.
        </div>
    </div>

    <div class="flexbox-item footer">
        Footer
    </div>
</div>

.flexbox-container
{
    //width: 100%;
    height: 100%;

    display: flex;
    flex-direction: column;

    justify-content: flex-start; /* align items in Main Axis */
    align-items: stretch; /* align items in Cross Axis */
    align-content: stretch; /* Extra space in Cross Axis */

    background: rgba(255, 255, 255, .1);
}

.flexbox-inner-container
{
    display: flex;
    flex-direction: row;

    justify-content: flex-start; /* flex-start is the default.  align items in Main Axis */
    align-items: stretch; /* stretch is default.  align items in Cross Axis */
    align-content: stretch; /* stretch is default. Extra space in Cross Axis */
}

.flexbox-item-grow
{
    flex: 1; /* same as flex: 1 1 auto; */
}

.fill-area-content
{
    overflow: auto; 
}

//Fluff below here
*, *:before, *:after
{
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}


html, body
{
    width: 100%;
    height: 100%;

    margin: 0;
    padding: 0;
}

.flexbox-item
{
    padding: 8px;
}

.flexbox-item.header
{
    background: rgba(255, 0, 0, .1);
}
.flexbox-item.footer
{
    background: rgba(0, 255, 0, .1);
}
.flexbox-item.
{
    background: rgba(0, 0, 255, .1);
}


body
{
    background: #444444;

    color: #cccccc;
    font-size: 14px;

    font-family: Frutiger, "Frutiger Linotype", Univers, Calibri, "Gill Sans", "Gill Sans MT", "Myriad Pro", Myriad, "DejaVu Sans Condensed", "Liberation Sans", "Nimbus Sans L", Tahoma, Geneva, "Helvetica Neue", Helvetica, Arial, sans-serif;

}

Answer 1

scrollTop 的最大值(因此您需要计算以确定滚动是否已移动到元素底部)将是 scrollHeight 减去高度元素的 - 根据您的描述，我会假设该元素是 115px 高。这是一个工作示例:

$('#foo').scroll(function() {
  var maxScrollTop = $(this).prop('scrollHeight') - $(this).height();
  if ($(this).scrollTop() == maxScrollTop) {
    console.log('scrolled to bottom!');
  }
});

#foo {
  height: 100px;
  overflow: scroll;
}
#content {
  height: 1000px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="foo">
  <div id="content">Scroll down!</div>
</div>