<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
ul,li {
list-style: none;
padding: 10px 15px;
border : 1px solid #333;
}
</style>
</head>
<boby>
<button class="btn1">Add1</button>
<button class="btn2">Add2</button>
<ul>
<li>list1</li>
<li>list2</li>
<li>list3</li>
<li>list4</li>
<li>list5</li>
</ul>
<script src="js/jquery-3.6.0.min.js"></script>
<script src="js/jquery-ui.min.js"></script>
<script>
var listLen = $("ul li").length;
$(".btn1").on("click", function() {
$("ul").append(`<li>list${++listLen}</li>`);
});
$(".btn2").on("click", function() {
$("ul").prepend(`<li>new list</li>`);
});
</script>
</boby>
</html>