我能够得到这个工作与CSS只。

诀窍在于:

display: flex;
flex-direction: column-reverse;

浏览器将底部视为顶部。假设您的目标浏览器支持灵活框，唯一需要注意的是标记必须以相反的顺序排列。

下面是一个工作示例。https://codepen.io/jimbol/pen/YVJzBg

以下是我的做法。div的高度是650px。我决定如果滚动高度在底部的150px范围内，那么自动滚动它。否则，留给用户。

if (container_block.scrollHeight - container_block.scrollTop < 800) {
                    container_block.scrollTo(0, container_block.scrollHeight);
}

我能够得到这个工作与CSS只。

诀窍在于:

display: flex;
flex-direction: column-reverse;

浏览器将底部视为顶部。假设您的目标浏览器支持灵活框，唯一需要注意的是标记必须以相反的顺序排列。

下面是一个工作示例。https://codepen.io/jimbol/pen/YVJzBg

$('#div1').scrollTop($('#div1')[0].scrollHeight);

Or animated:

$("#div1").animate({ scrollTop: $('#div1')[0].scrollHeight}, 1000);

我设法把它修好了。诀窍是计算:(a)当前div用户滚动位置和(b) div滚动高度，都是在附加新元素之前。

如果a === b，则在追加新元素之前就知道用户位于底部。

    let div = document.querySelector('div.scrollableBox');

    let span = document.createElement('span');
    span.textContent = 'Hello';

    let divCurrentUserScrollPosition = div.scrollTop + div.offsetHeight;
    let divScrollHeight = div.scrollHeight;

    // We have the current scroll positions saved in
    // variables, so now we can append the new element.
    div.append(span);

    
    if ((divScrollHeight === divCurrentUserScrollPosition)) {
        // Scroll to bottom of div
        div.scrollTo({ left: 0, top: div.scrollHeight });
    }

我不能让前两个答案工作，其他答案都对我没有帮助。所以我从Reddit r/forhire和Upwork上给了三个人30美元，得到了一些非常好的答案。这个答案可以帮你省下90美元。

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Justin Hundley / The Site Bros的解决方案

HTML

<div id="chatscreen">
  <div id="inner">
  
  </div>
</div>

CSS

#chatscreen {
  width: 300px;
  overflow-y: scroll;
  max-height:100px;
}

Javascript

$(function(){
    var scrolled = false;
  var lastScroll = 0;
  var count = 0;
    $("#chatscreen").on("scroll", function() {
    var nextScroll = $(this).scrollTop();

    if (nextScroll <= lastScroll) {
        scrolled = true;
    }
    lastScroll = nextScroll;
    
    console.log(nextScroll, $("#inner").height())
    if ((nextScroll + 100) == $("#inner").height()) {
        scrolled = false;
    }
  });
 
  function updateScroll(){
      if(!scrolled){
          var element = document.getElementById("chatscreen");
          var inner = document.getElementById("inner");
          element.scrollTop = inner.scrollHeight;
      }
  }

  // Now let's load our messages
  function load_messages(){
      $( "#inner" ).append( "Test" + count + "<br/>" );
      count = count + 1;
      updateScroll();
  }

    setInterval(load_messages,300); 
});

预览网站兄弟的解决方案

投资组合

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莱尔梅克斯/斯维亚托斯拉夫·丘马科夫的解决方案

HTML

<div id="chatscreen">

</div>

CSS

#chatscreen {
  height: 300px;
  border: 1px solid purple;
  overflow: scroll;
}

Javascript

$(function(){
var isScrolledToBottom = false;
// Now let's load our messages
function load_messages(){
    $( "#chatscreen" ).append( "<br>Test" );
    updateScr();
}

var out = document.getElementById("chatscreen");
var c = 0;

$("#chatscreen").on('scroll', function(){
        console.log(out.scrollHeight);
    isScrolledToBottom = out.scrollHeight - out.clientHeight <= out.scrollTop + 10;
});

function updateScr() {
        // allow 1px inaccuracy by adding 1
    //console.log(out.scrollHeight - out.clientHeight,  out.scrollTop + 1);
    var newElement = document.createElement("div");

    newElement.innerHTML = c++;
    out.appendChild(newElement);
    
    console.log(isScrolledToBottom);

    // scroll to bottom if isScrolledToBotto
    if(isScrolledToBottom) {out.scrollTop = out.scrollHeight - out.clientHeight; }
}

var add = setInterval(updateScr, 1000);

setInterval(load_messages,300); // change to 300 to show the latest message you sent after pressing enter // comment this line and it works, uncomment and it fails
                                // leaving it on 1000 shows the second to last message
setInterval(updateScroll,30);
});

预览Sviatoslav的解决方案

投资组合

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伊戈尔·鲁西诺夫的解决方案

HTML

<div id="chatscreen"></div>

CSS

#chatscreen {
  height: 100px;
  overflow: scroll;
  border: 1px solid #000;
}

Javascript

$(function(){

// Now let's load our messages
function load_messages(){
    $( "#chatscreen" ).append( "<br>Test" );
}

var out = document.getElementById("chatscreen");
var c = 0;
var add = setInterval(function() {
    // allow 1px inaccuracy by adding 1
    var isScrolledToBottom = out.scrollHeight - out.clientHeight <= out.scrollTop + 1;
    load_messages();

    // scroll to bottom if isScrolledToBotto
    if(isScrolledToBottom) {out.scrollTop = out.scrollHeight - out.clientHeight; }
}, 1000);
setInterval(updateScroll,30);
});

预览Igor的解决方案

投资组合