<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>jq之demo</title>
<!--线上jq库-->
<script src="https://code.jquery.com/jquery-3.4.1.min.js"></script>
<script>
$(document).ready(function(){
$("button").click(function(){
/*$("ul li:first")指定第一个ul的第一个li元素*/
$("ul li:first").hide();
});
});
</script>
</head>
<body>
<p>List 1:</p>
<ul>
<li>Coffee</li>
<li>Milk</li>
<li>Tea</li>
</ul>
<p>List 2:</p>
<ul>
<li>Coffee</li>
<li>Milk</li>
<li>Tea</li>
</ul>
<button>点我</button>
</body>
</html>