因项目需要实现消息通知上下无缝轮播的效果，所以写了一下，在这个分享出来，希望再次遇到此需求的道友，可以直接拷贝来用，节约一点不必要的时间。
原生JS版本
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>文字上下无缝轮播</title>
</head>
<style>
* {
margin: 0;
padding: 0;
}
#container{
width: 60%;
margin: 100px auto;
position: relative;
height: 200px;
overflow: hidden;
}
#list-wrapper{
position: relative;
}
ul {
list-style: none;
background: #f8f8f8;
text-align: center;
padding: 0 20px;
}
li{
height: 35px;
line-height: 35px;
color: #fff;
}
li:nth-child(odd){
background: #5077aa;
}
li:nth-child(even){
background: #fb6b06;
}
</style>
<body>
<div id="container">
<div id="list-wrapper" style="top: 0">
<ul class="notice-list" id="notice-list">
<li>富强、*、文明、和谐、*1</li>
<li>富强、*、文明、和谐、*2</li>
<li>富强、*、文明、和谐、*3</li>
<li>富强、*、文明、和谐、*4</li>
<li>富强、*、文明、和谐、*5</li>
<li>富强、*、文明、和谐、*6</li>
</ul>
<ul class="notice-list" id="notice-list-2">
</ul>
</div>
</div>
<script>
var ROLL_SPEED = 100
var noticeList1 = document.getElementById('notice-list');
var noticeList2 = document.getElementById('notice-list-2');
var listWrapper = document.getElementById('list-wrapper');
noticeList2.innerHTML=noticeList1.innerHTML;
var timer = setInterval(rollStart, ROLL_SPEED);
function rollStart() {
if (Math.abs(_subStr(listWrapper.style.top)) >= noticeList1.clientHeight) {
listWrapper.style.top = '0px'
} else {
var top = listWrapper.style.top
listWrapper.style.top = _subStr(top)-1+'px'
}
}
// 截取px前数值
function _subStr(str) {
var index = str.indexOf('px');
if (index > -1) {
return parseFloat(str.substr(0, index + 1))
}
}
</script>
</body>
</html>
jQuery版本
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>文字上下无缝轮播</title>
</head>
<style>
* {
margin: 0;
padding: 0;
}
#container{
width: 60%;
margin: 100px auto;
position: relative;
height: 200px;
overflow: hidden;
}
#list-wrapper{
position: relative;
top: 0;
}
ul {
list-style: none;
background: #f8f8f8;
text-align: center;
padding: 0 20px;
}
li{
height: 35px;
line-height: 35px;
color: #fff;
}
li:nth-child(odd){
background: #5077aa;
}
li:nth-child(even){
background: #fb6b06;
}
</style>
<body>
<div id="container">
<div id="list-wrapper">
<ul class="notice-list" id="notice-list">
<li>富强、*、文明、和谐、*1</li>
<li>富强、*、文明、和谐、*2</li>
<li>富强、*、文明、和谐、*3</li>
<li>富强、*、文明、和谐、*4</li>
<li>富强、*、文明、和谐、*5</li>
<li>富强、*、文明、和谐、*6</li>
</ul>
<ul class="notice-list" id="notice-list-2">
</ul>
</div>
</div>
<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
<script>
var ROLL_SPEED = 100
var noticeList1 = $('#notice-list');
var noticeList2 = $('#notice-list-2');
var listWrapper = $('#list-wrapper');
noticeList2.html(noticeList1.html())
listWrapper.css('top', 0)
var timer = setInterval(rollStart, ROLL_SPEED);
function rollStart() {
if (Math.abs(_subStr(listWrapper.css('top'))) >= noticeList1.height()) {
listWrapper.css('top', 0)
} else {
var top = listWrapper.css('top');
listWrapper.css('top', _subStr(top) - 1)
}
}
// 截取px前数值
function _subStr(str) {
var index = str.indexOf('px');
if (index > -1) {
return parseFloat(str.substr(0, index + 1))
}
}
</script>
</body>
</html>