index.html
<!DOCTYPE html>
<html lang="ja">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>jQueryの練習</title>
<style>
.red-text{
color: red;
font-weight: bold;
}
</style>
</head>
<body>
<button>Go!</button>
<p>こんにちは！</p>
<script src="https://code.jquery.com/jquery-3.7.1.min.js" integrity="sha256-/JqT3SQfawRcv/BIHPThkBvs0OEvtFFmqPF/lYI/Cxo=" crossorigin="anonymous"></script>
<script src="js/main.js"></script>
</body>
</html>main.js
'use strict';
$(() => {
$('button').click(() => {
// $('p').text('おはよう！');
// $('p').addClass('red-text');
$('p')
.text('おはよう！')
.addClass('red-text');
});
});