我有一个只有 300 像素大的 div,我希望它在页面加载时滚动到内容的底部。这个 div 有动态添加的内容,需要一直向下滚动。现在,如果用户决定向上滚动,我不希望它跳回底部,直到用户再次向下滚动
是否有可能让一个 div 保持滚动到底部,除非用户向上滚动并且当用户滚动回底部时,即使添加了新的动态内容,它也需要将自己保持在底部。我将如何去创造这个。
我有一个只有 300 像素大的 div,我希望它在页面加载时滚动到内容的底部。这个 div 有动态添加的内容,需要一直向下滚动。现在,如果用户决定向上滚动,我不希望它跳回底部,直到用户再次向下滚动
是否有可能让一个 div 保持滚动到底部,除非用户向上滚动并且当用户滚动回底部时,即使添加了新的动态内容,它也需要将自己保持在底部。我将如何去创造这个。
我只能使用 CSS 来实现它。
诀窍是使用display: flex;
和flex-direction: column-reverse;
浏览器将底部视为顶部。假设您的目标浏览器 support flex-box
,唯一需要注意的是标记必须以相反的顺序排列。
这是一个工作示例。https://codepen.io/jimbol/pen/YVJzBg
这可能会帮助您:
var element = document.getElementById("yourDivID");
element.scrollTop = element.scrollHeight;
[编辑],以匹配评论...
function updateScroll(){
var element = document.getElementById("yourDivID");
element.scrollTop = element.scrollHeight;
}
每当添加内容时,调用函数 updateScroll(),或设置一个计时器:
//once a second
setInterval(updateScroll,1000);
如果您只想在用户没有移动的情况下更新:
var scrolled = false;
function updateScroll(){
if(!scrolled){
var element = document.getElementById("yourDivID");
element.scrollTop = element.scrollHeight;
}
}
$("#yourDivID").on('scroll', function(){
scrolled=true;
});
我刚刚实现了这个,也许你可以使用我的方法。
假设我们有以下 HTML:
<div id="out" style="overflow:auto"></div>
然后我们可以检查它是否滚动到底部:
var out = document.getElementById("out");
// allow 1px inaccuracy by adding 1
var isScrolledToBottom = out.scrollHeight - out.clientHeight <= out.scrollTop + 1;
scrollHeight为您提供元素的高度,包括由于溢出而导致的任何不可见区域。clientHeight为您提供 CSS 高度,或者以另一种方式说,元素的实际高度。两种方法都返回没有 的高度margin
,因此您不必担心。scrollTop为您提供垂直滚动的位置。0 是顶部,最大值是元素的滚动高度减去元素本身的高度。使用滚动条时,很难(对我来说是在 Chrome 中)将滚动条一直向下移动到底部。所以我投入了 1px 的误差。isScrolledToBottom
即使滚动条距离底部 1px 也是如此。您可以将其设置为适合您的任何内容。
然后只需将元素的 scrollTop 设置到底部即可。
if(isScrolledToBottom)
out.scrollTop = out.scrollHeight - out.clientHeight;
我为你做了一个小提琴来展示这个概念:http: //jsfiddle.net/dotnetCarpenter/KpM5j/
编辑:添加了代码片段以阐明何时isScrolledToBottom
是true
.
将滚动条粘贴到底部
const out = document.getElementById("out")
let c = 0
setInterval(function() {
// allow 1px inaccuracy by adding 1
const isScrolledToBottom = out.scrollHeight - out.clientHeight <= out.scrollTop + 1
const newElement = document.createElement("div")
newElement.textContent = format(c++, 'Bottom position:', out.scrollHeight - out.clientHeight, 'Scroll position:', out.scrollTop)
out.appendChild(newElement)
// scroll to bottom if isScrolledToBottom is true
if (isScrolledToBottom) {
out.scrollTop = out.scrollHeight - out.clientHeight
}
}, 500)
function format () {
return Array.prototype.slice.call(arguments).join(' ')
}
#out {
height: 100px;
}
<div id="out" style="overflow:auto"></div>
<p>To be clear: We want the scrollbar to stick to the bottom if we have scrolled all the way down. If we scroll up, then we don't want the content to move.
</p>
2020 年可以使用css snap,但在 Chrome 81 之前布局更改不会触发 re-snap,纯 css 聊天 ui可以在 Chrome 81 上运行,您也可以检查Can I use CSS snap。
此演示将捕捉最后一个元素(如果可见),滚动到底部以查看效果。
.container {
overflow-y: scroll;
overscroll-behavior-y: contain;
scroll-snap-type: y proximity;
}
.container > div > div:last-child {
scroll-snap-align: end;
}
.container > div > div {
background: lightgray;
height: 3rem;
font-size: 1.5rem;
}
.container > div > div:nth-child(2n) {
background: gray;
}
<div class="container" style="height:6rem">
<div>
<div>1</div>
<div>2</div>
<div>3</div>
<div>4</div>
<div>5</div>
</div>
</div>
编辑
使用scroll-snap-type: y proximity;
,向上滚动更容易。
$('#yourDiv').scrollTop($('#yourDiv')[0].scrollHeight);
现场演示:http: //jsfiddle.net/KGfG2/
$('#div1').scrollTop($('#div1')[0].scrollHeight);
Or animated:
$("#div1").animate({ scrollTop: $('#div1')[0].scrollHeight}, 1000);
.cont{
height: 100px;
overflow-x: hidden;
overflow-y: auto;
transform: rotate(180deg);
direction:rtl;
text-align:left;
}
ul{
overflow: hidden;
transform: rotate(180deg);
}
<div class="cont">
<ul>
<li>0</li>
<li>1</li>
<li>2</li>
<li>3</li>
<li>4</li>
<li>5</li>
<li>6</li>
<li>7</li>
<li>8</li>
<li>9</li>
<li>10</li>
</ul>
</div>
Run code snippet
看看效果。(PS:如果Run code snippet
不工作,试试这个:https ://jsfiddle.net/Yeshen/xm2yLksu/3/ )
它是如何工作的:
默认溢出是从上到下滚动。
transform: rotate(180deg)
可以让它从下到上滚动或加载动态块。
这是基于Ryan Hunt 的博客文章的解决方案。它取决于overflow-anchor
CSS 属性,它将滚动位置固定到滚动内容底部的元素。
function addMessage() {
const $message = document.createElement('div');
$message.className = 'message';
$message.innerText = `Random number = ${Math.ceil(Math.random() * 1000)}`;
$messages.insertBefore($message, $anchor);
// Trigger the scroll pinning when the scroller overflows
if (!overflowing) {
overflowing = isOverflowing($scroller);
$scroller.scrollTop = $scroller.scrollHeight;
}
}
function isOverflowing($el) {
return $el.scrollHeight > $el.clientHeight;
}
const $scroller = document.querySelector('.scroller');
const $messages = document.querySelector('.messages');
const $anchor = document.querySelector('.anchor');
let overflowing = false;
setInterval(addMessage, 1000);
.scroller {
overflow: auto;
height: 90vh;
max-height: 11em;
background: #555;
}
.messages > * {
overflow-anchor: none;
}
.anchor {
overflow-anchor: auto;
height: 1px;
}
.message {
margin: .3em;
padding: .5em;
background: #eee;
}
<section class="scroller">
<div class="messages">
<div class="anchor"></div>
</div>
</section>
请注意,overflow-anchor
目前在 Safari 中不起作用。
$('#yourDivID').animate({ scrollTop: $(document).height() }, "slow");
return false;
这将从#yourDivID
使用该$(document).height()
属性的高度计算 ScrollTop 位置,因此即使将动态内容添加到 div 滚动条也将始终位于底部位置。希望这可以帮助。但是它也有一个小错误,即使我们向上滚动并将鼠标指针从滚动条上移开,它也会自动到达底部位置。如果有人可以纠正这一点,那就太好了。
我无法得到前两个答案,其他答案都对我没有帮助。所以我从 Reddit r/forhire和Upwork向三个人支付了 30 美元,得到了一些非常好的答案。这个答案应该可以为您节省 90 美元。
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);
});
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);
});
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);
});
//Make sure message list is scrolled to the bottom
var container = $('#MessageWindowContent')[0];
var containerHeight = container.clientHeight;
var contentHeight = container.scrollHeight;
container.scrollTop = contentHeight - containerHeight;
这是我基于 dotnetCarpenter 的回答的版本。我的方法是纯 jQuery,我为变量命名以使事情更清晰。发生的情况是,如果内容高度大于容器,我们向下滚动额外的距离以获得所需的结果。
适用于 IE 和 chrome..
吉姆霍尔的答案是可取的,因为当你向上滚动时它确实不会滚动到底部,它也是纯 CSS。
然而,非常不幸的是,这不是一个稳定的解决方案:在 chrome 中(可能是由于上面 dotnetCarpenter 描述的 1-px 问题)scrollTop
,即使没有用户交互(在添加元素时),其行为也会有 1 个像素的不准确。您可以设置scrollTop = scrollHeight - clientHeight
,但是当添加另一个元素时,这将使 div 保持在原位,即“将自身保持在底部”功能不再起作用。
因此,简而言之,添加少量 Javascript(叹气)将解决此问题并满足所有要求:
像https://codepen.io/anon/pen/pdrLEZ这样的东西(Coo 的例子),在向列表中添加一个元素之后,还有以下内容:
container = ...
if(container.scrollHeight - container.clientHeight - container.scrollTop <= 29) {
container.scrollTop = container.scrollHeight - container.clientHeight;
}
其中 29 是一条线的高度。
因此,当用户向上滚动半行时(如果可能的话?),Javascript 将忽略它并滚动到底部。但我想这是可以忽略的。而且,它修复了 Chrome 1 px 的东西。
你可以使用这样的东西,
var element = document.getElementById("yourDivID");
window.scrollTo(0,element.offsetHeight);
以下是您需要的(我尽了最大努力,一路上进行了大量的谷歌搜索):
<html>
<head>
<script>
// no jquery, or other craziness. just
// straight up vanilla javascript functions
// to scroll a div's content to the bottom
// if the user has not scrolled up. Includes
// a clickable "alert" for when "content" is
// changed.
// this should work for any kind of content
// be it images, or links, or plain text
// simply "append" the new element to the
// div, and this will handle the rest as
// proscribed.
let scrolled = false; // at bottom?
let scrolling = false; // scrolling in next msg?
let listener = false; // does element have content changed listener?
let contentChanged = false; // kind of obvious
let alerted = false; // less obvious
function innerHTMLChanged() {
// this is here in case we want to
// customize what goes on in here.
// for now, just:
contentChanged = true;
}
function scrollToBottom(id) {
if (!id) { id = "scrollable_element"; }
let DEBUG = 0; // change to 1 and open console
let dstr = "";
let e = document.getElementById(id);
if (e) {
if (!listener) {
dstr += "content changed listener not active\n";
e.addEventListener("DOMSubtreeModified", innerHTMLChanged);
listener = true;
} else {
dstr += "content changed listener active\n";
}
let height = (e.scrollHeight - e.offsetHeight); // this isn't perfect
let offset = (e.offsetHeight - e.clientHeight); // and does this fix it? seems to...
let scrollMax = height + offset;
dstr += "offsetHeight: " + e.offsetHeight + "\n";
dstr += "clientHeight: " + e.clientHeight + "\n";
dstr += "scrollHeight: " + e.scrollHeight + "\n";
dstr += "scrollTop: " + e.scrollTop + "\n";
dstr += "scrollMax: " + scrollMax + "\n";
dstr += "offset: " + offset + "\n";
dstr += "height: " + height + "\n";
dstr += "contentChanged: " + contentChanged + "\n";
if (!scrolled && !scrolling) {
dstr += "user has not scrolled\n";
if (e.scrollTop != scrollMax) {
dstr += "scroll not at bottom\n";
e.scroll({
top: scrollMax,
left: 0,
behavior: "auto"
})
e.scrollTop = scrollMax;
scrolling = true;
} else {
if (alerted) {
dstr += "alert exists\n";
} else {
dstr += "alert does not exist\n";
}
if (contentChanged) { contentChanged = false; }
}
} else {
dstr += "user scrolled away from bottom\n";
if (!scrolling) {
dstr += "not auto-scrolling\n";
if (e.scrollTop >= scrollMax) {
dstr += "scroll at bottom\n";
scrolled = false;
if (alerted) {
dstr += "alert exists\n";
let n = document.getElementById("alert");
n.remove();
alerted = false;
contentChanged = false;
scrolled = false;
}
} else {
dstr += "scroll not at bottom\n";
if (contentChanged) {
dstr += "content changed\n";
if (!alerted) {
dstr += "alert not displaying\n";
let n = document.createElement("div");
e.append(n);
n.id = "alert";
n.style.position = "absolute";
n.classList.add("normal-panel");
n.classList.add("clickable");
n.classList.add("blink");
n.innerHTML = "new content!";
let nposy = parseFloat(getComputedStyle(e).height) + 18;
let nposx = 18 + (parseFloat(getComputedStyle(e).width) / 2) - (parseFloat(getComputedStyle(n).width) / 2);
dstr += "nposx: " + nposx + "\n";
dstr += "nposy: " + nposy + "\n";
n.style.left = nposx;
n.style.top = nposy;
n.addEventListener("click", () => {
dstr += "clearing alert\n";
scrolled = false;
alerted = false;
contentChanged = false;
n.remove();
});
alerted = true;
} else {
dstr += "alert already displayed\n";
}
} else {
alerted = false;
}
}
} else {
dstr += "auto-scrolling\n";
if (e.scrollTop >= scrollMax) {
dstr += "done scrolling";
scrolling = false;
scrolled = false;
} else {
dstr += "still scrolling...\n";
}
}
}
}
if (DEBUG && dstr) console.log("stb:\n" + dstr);
setTimeout(() => { scrollToBottom(id); }, 50);
}
function scrollMessages(id) {
if (!id) { id = "scrollable_element"; }
let DEBUG = 1;
let dstr = "";
if (scrolled) {
dstr += "already scrolled";
} else {
dstr += "got scrolled";
scrolled = true;
}
dstr += "\n";
if (contentChanged && alerted) {
dstr += "content changed, and alerted\n";
let n = document.getElementById("alert");
if (n) {
dstr += "alert div exists\n";
let e = document.getElementById(id);
let nposy = parseFloat(getComputedStyle(e).height) + 18;
dstr += "nposy: " + nposy + "\n";
n.style.top = nposy;
} else {
dstr += "alert div does not exist!\n";
}
} else {
dstr += "content NOT changed, and not alerted";
}
if (DEBUG && dstr) console.log("sm: " + dstr);
}
setTimeout(() => { scrollToBottom("messages"); }, 1000);
/////////////////////
// HELPER FUNCTION
// simulates adding dynamic content to "chat" div
let count = 0;
function addContent() {
let e = document.getElementById("messages");
if (e) {
let br = document.createElement("br");
e.append("test " + count);
e.append(br);
count++;
}
}
</script>
<style>
button {
border-radius: 5px;
}
#container {
padding: 5px;
}
#messages {
background-color: blue;
border: 1px inset black;
border-radius: 3px;
color: white;
padding: 5px;
overflow-x: none;
overflow-y: auto;
max-height: 100px;
width: 100px;
margin-bottom: 5px;
text-align: left;
}
.bordered {
border: 1px solid black;
border-radius: 5px;
}
.inline-block {
display: inline-block;
}
.centered {
text-align: center;
}
.normal-panel {
background-color: #888888;
border: 1px solid black;
border-radius: 5px;
padding: 2px;
}
.clickable {
cursor: pointer;
}
</style>
</head>
<body>
<div id="container" class="bordered inline-block centered">
<div class="inline-block">My Chat</div>
<div id="messages" onscroll="scrollMessages('messages')">
test<br>
test<br>
test<br>
test<br>
test<br>
test<br>
test<br>
test<br>
test<br>
test<br>
</div>
<button onclick="addContent();">Add Content</button>
</div>
</body>
</html>
注意:您可能需要同时调整警报位置(nposx
和nposy
)以符合您的需要...scrollToBottom
scrollMessages
还有一个链接到我自己的工作示例,托管在我的服务器上:https ://night-stand.ca/jaretts_tests/chat_scroll.html
基于曼哈顿先生的解决方案和评论。https://stackoverflow.com/a/18614545/9208887。
我还添加了一个元素,flex 1 1 0%
以确保文本在容器未满时从顶部开始。
// just to add some numbers, so we can see the effect
// the actual solution requires no javascript
let num = 1001;
const container = document.getElementById("scroll-container");
document.getElementById("adder").onclick = () =>
container.append(
Object.assign(document.createElement("div"), {
textContent: num++
})
);
.scroll-wrapper {
height: 100px;
overflow: auto;
display: flex;
flex-direction: column-reverse;
border: 1px solid black;
}
.scroll-start-at-top {
flex: 1 1 0%;
}
<div class="scroll-wrapper">
<span class="scroll-start-at-top"></span>
<div id="scroll-container">
<div>1000</div>
</div>
</div>
<button id="adder">Add Text</button>
这是我的处理方式。我的 div 高度是 650 像素。我决定如果滚动高度在底部的 150px 范围内,则自动滚动它。否则,留给用户。
if (container_block.scrollHeight - container_block.scrollTop < 800) {
container_block.scrollTo(0, container_block.scrollHeight);
}
我设法让这个工作。诀窍是计算:(a)当前 div 用户滚动位置和(b)div 滚动高度,两者都在添加新元素之前。
如果 a === b,我们知道用户在添加新元素之前位于底部。
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 });
}
我试图对 Bootstrap 5 做同样的事情。我正在编写的页面是一个单窗口 html 工具,我希望两列具有可滚动的内容,并且一个需要反转,因为它是一个日志(另一个不太可能滚动,除非故意这样做)。列表和它们的标题也是底部锚定的,我很难让标题保持在弹性可滚动列表的顶部。
多亏了上面的例子,我可以弄清楚我缺少什么并获得正确的类类型来使其工作。
这是我的完整示例。在我的实际应用程序中,其他两列左侧有第三列,mh-100 col overflow-auto
并且不需要内部行/列,因为没有标题可以粘贴在顶部(如果视口太小,它将正常滚动)。这些列表有一个 ID,用于选择和添加它们或删除顶部元素(这是<li>
反向列表中的底部项目)。
这里提供了一个较小的版本:
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" crossorigin="anonymous">
<div class="vh-100 w-75 container-fluid">
<h1>2nd Level Scrolling Example</h1>
<div class="h-75 row align-items-end">
<div class="mh-100 col d-flex flex-column">
<div class="row align-items-end">
<div class="col"><h3>Normal scroll list, grow on top</h3></div>
</div>
<div class="row align-items-end overflow-auto">
<div class="mh-100 col">
<ul class="list-group">
<li>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin ut</li>
<li>tortor eu ex tincidunt pretium non eu nisl. Ut eu libero ac velit</li>
<li>ultricies dapibus. Donec id augue scelerisque, gravida est ut,</li>
<li>commodo sapien. Interdum et malesuada fames ac ante ipsum primis</li>
<li>in faucibus. Suspendisse volutpat fermentum finibus. Cras egestas</li>
<li>tempor tempor. Suspendisse potenti. Mauris ac tellus ultrices lectus</li>
<li>accumsan pellentesque. Nullam semper, nisi nec euismod ultrices, leo</li>
<li>sem bibendum sapien, in rutrum sapien massa id mi.</li>
</ul>
</div>
</div>
</div>
<div class="mh-100 col d-flex flex-column">
<div class="row align-items-end">
<div class="col"><h3>Reverse scroll list, grow on bottom</h3></div>
</div>
<div class="row align-items-end d-flex flex-column-reverse overflow-auto">
<div class="mh-100 col">
<ul class="list-group">
<li>sem bibendum sapien, in rutrum sapien massa id mi.</li>
<li>accumsan pellentesque. Nullam semper, nisi nec euismod ultrices, leo</li>
<li>tempor tempor. Suspendisse potenti. Mauris ac tellus ultrices lectus</li>
<li>in faucibus. Suspendisse volutpat fermentum finibus. Cras egestas</li>
<li>commodo sapien. Interdum et malesuada fames ac ante ipsum primis</li>
<li>ultricies dapibus. Donec id augue scelerisque, gravida est ut,</li>
<li>tortor eu ex tincidunt pretium non eu nisl. Ut eu libero ac velit</li>
<li>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin ut</li>
</ul>
</div>
</div>
</div>
</div>
</div>
如果您的视口高度小于整体内容,则标题应位于列表顶部,页面底部的所有内容(实际上是视口高度的 75%,但在本例中,标题不占用空间它是为)而设计的。
注意:我并不是真正的网络开发人员,只是为日常工作编写一些方便的基于 html 的工具,因此非常欢迎发表评论。