<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<ul></ul>
<script src="jquery-3.4.1.js"></script>
<script>
console.log($('<li class="dzm">content</li>'));
$('ul').html('<li class="dzm">content</li>')
</script>
</body>
</html>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script src="jquery-3.4.1.js"></script>
<script>
$(document).ready(function () {
$('button').click(function () {
var jqNewLi = $('<li>new dzm</li>');
$('li').before(jqNewLi)
})
})
</script>
</head>
<body>
<button>添加li</button>
<ul>
<li>dzm</li>
</ul>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script src="jquery-3.4.1.js"></script>
<script>
$(document).ready(function () {
$('button:eq(0)').click(function () {
$('ul').empty();
})
$('button:eq(1)').click(function () {
})
})
</script>
</head>
<body>
<button>清空li</button>
<button>删除第一个li</button>
<ul>
<li>dzm1</li>
<li>dzm2</li>
<li>dzm3</li>
</ul>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script src="jquery-3.4.1.js"></script>
<script>
$(document).ready(function () {
$('button').click(function () {
var newUl = $('.box ul').clone();
$('.box').append(newUl);
})
})
</script>
</head>
<body>
<button>复制节点</button>
<div class="box">
<ul>
<li>dzm1</li>
<li>dzm2</li>
<li>dzm3</li>
</ul>
</div>
</body>
</html>
