我正在制作一个基本的聊天网站，我使用了一些来自bootstrap的预定义类作为我的模态表单，作为与我自己的一些CSS相结合的聊天表单，问题是每次用户打开聊天表单模态时，显示消息的表单(具有溢出的CSS属性：滚动；(内的输出总是开始显示最旧的消息，用户必须向下滚动才能显示最新消息，我从这里的一个问题中找到了一个脚本，使输出显示最新的消息，但现在我无法再滚动到顶部：(
这是3个表单输出的脚本
<script>
const messages0 = document.getElementById('output0');
const messages1 = document.getElementById('output1');
const messages2 = document.getElementById('output2');
function getMessages() {
// Prior to getting your messages.
shouldScroll0 = messages0.scrollTop + messages0.clientHeight === messages0.scrollHeight;
shouldScroll1 = messages1.scrollTop + messages1.clientHeight === messages1.scrollHeight;
shouldScroll2 = messages2.scrollTop + messages2.clientHeight === messages2.scrollHeight;
// After getting your messages.
if (!shouldScroll0) {
scrollToBottom(messages0);
}
if (!shouldScroll1) {
scrollToBottom(messages1);
}
if (!shouldScroll2) {
scrollToBottom(messages2);
}
}
function scrollToBottom() {
messages0.scrollTop = messages0.scrollHeight;
messages1.scrollTop = messages1.scrollHeight;
messages2.scrollTop = messages2.scrollHeight;
}
scrollToBottom();
setInterval(getMessages, 100);
</script>*here is the CSS of the output and variables inside of it
<style>
.message-blue {
position: relative;
margin-left: 20px;
margin-bottom: 10px;
padding: 10px;
background-color: #A8DDFD;
width: 200px;
height: auto;
text-align: left;
font: 400 .9em 'Open Sans', sans-serif;
border: 1px solid #97C6E3;
border-radius: 10px;
}
.message-orange {
position: relative;
margin-bottom: 10px;
margin-left: calc(100% - 240px);
padding: 10px;
background-color: #f8e896;
width: 200px;
height: auto;
text-align: left;
font: 400 .9em 'Open Sans', sans-serif;
border: 1px solid #dfd087;
border-radius: 10px;
}
.message-content {
padding: 0;
margin: 0;
}
.message-timestamp-right {
position: absolute;
font-size: .85em;
font-weight: 300;
bottom: 5px;
right: 5px;
}
.message-timestamp-left {
position: absolute;
font-size: .85em;
font-weight: 300;
bottom: 5px;
left: 5px;
}
.message-blue:after {
content: '';
position: absolute;
width: 0;
height: 0;
border-top: 15px solid #A8DDFD;
border-left: 15px solid transparent;
border-right: 15px solid transparent;
top: 0;
left: -15px;
}
.message-blue:before {
content: '';
position: absolute;
width: 0;
height: 0;
border-top: 17px solid #97C6E3;
border-left: 16px solid transparent;
border-right: 16px solid transparent;
top: -1px;
left: -17px;
}
.message-orange:after {
content: '';
position: absolute;
width: 0;
height: 0;
border-bottom: 15px solid #f8e896;
border-left: 15px solid transparent;
border-right: 15px solid transparent;
bottom: 0;
right: -15px;
}
.message-orange:before {
content: '';
position: absolute;
width: 0;
height: 0;
border-bottom: 17px solid #dfd087;
border-left: 16px solid transparent;
border-right: 16px solid transparent;
bottom: -1px;
right: -17px;
}
.output{
border: 2px solid gray;
background-color: #f1f1f1;
border-radius: 5px;
padding: 5px;
margin: 10px 0;
overflow: scroll;
height: 250px;
}
</style>and here is the HTML of 1 modal form output
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Home page chat application</title>
<script src="https://code.jquery.com/jquery-2.1.4.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" rel="stylesheet" type="text/css" />
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap3-dialog/1.34.9/css/bootstrap-dialog.css" rel="stylesheet" type="text/css" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap3-dialog/1.34.9/js/bootstrap-dialog.js"></script>
</head>
<body>
<div id="output0" class="output">
<?php
---some php related to the db insertion of new messages----
?>
<?php
include ("ConfigFile.php");
$name=$_SESSION["user"];
$seqo = "SELECT * FROM `adminposts` WHERE `Group_by` = 'Admin' AND `admin_id`='606' or `Group_by` = '606E'";
$resu=$link->query($seqo);
if ($resu->num_rows != 0){
while($row = $resu->fetch_assoc()){
if($row["Group_by"]=='Admin'){
echo "<h3 style='color:red;'>".$row["name"]." --".$row["date"]." "."<br> :<div id='messagess'>".$row["msg"]."</div><br> *Announcement* <br> </h3>";}
if($row["name"]=="$name"){
echo "<div class='message-blue'>";
echo "<h4>".$row["name"]."</h4>";
echo "<div class = 'message-content' id='messagess'>".$row["msg"]."</div> <br>";
echo "<div class='message-timestamp-left'>".$row["date"]."</div>";
echo "</div>";}
if($row["Group_by"] !== 'Admin' && $row["name"]!=="$name") { echo "<div class='message-orange'>";
echo "<h4>".$row["name"]."</h4>";
echo "<p class = 'message-content'>".$row["msg"]."</p> <br>";
echo "<div class='message-timestamp-right'>".$row["date"]."</div>";
echo "</div>";}
}
}
else {
echo "no messages were displayed yet.";
}
$link->close();
?>
</div>
</div>
</body>请帮忙：'(脚本中的if语句可能会给用户滚动的选项，并且只有当用户提交消息或打开模态时，输出才会自动显示最新的输出，而不滚动
所以我发现，正如我所说，一个小的if/else语句就可以了，我测试了几个选项，这对我来说很有效：
else {
$("#output2 #output1 #output0").on('scroll', function(){
scrollToBottom=false;});}
它被添加到(！shouldScroll(的if语句中
所以整个脚本应该是这样的：
<script>
const messages0 = document.getElementById('output0');
const messages1 = document.getElementById('output1');
const messages2 = document.getElementById('output2');
function getMessages() {
// Prior to getting your messages.
shouldScroll0 = messages0.scrollTop + messages0.clientHeight === messages0.scrollHeight;
shouldScroll1 = messages1.scrollTop + messages1.clientHeight === messages1.scrollHeight;
shouldScroll2 = messages2.scrollTop + messages2.clientHeight === messages2.scrollHeight;
// After getting your messages.
if (!shouldScroll0) {
scrollToBottom(messages0.scrollTop);
}
if (!shouldScroll1) {
scrollToBottom(messages1.scrollTop);
}
if (!shouldScroll2) {
scrollToBottom(messages2.scrollTop);
}
else {
$("#output2 #output1 #output0").on('scroll', function(){
scrollToBottom=false;
});
}
}
function scrollToBottom() {
messages0.scrollTop = messages0.scrollHeight;
messages1.scrollTop = messages1.scrollHeight;
messages2.scrollTop = messages2.scrollHeight;
}
scrollToBottom();
setInterval(getMessages, 100);
</script>这样，当用户打开聊天表单时，它会自动显示最新的消息，也会在提交消息后显示最新消息，但如果用户滚动到顶部，它将被允许