HTML
13<!DOCTYPE html>
<html>
<head>
<title>RSSリーダー</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="app4.js"></script>
</head>
<body>
<div class="container">
<h1>RSSリーダー</h1>
<form class="form-inline">
<div class="form-group">
<label for="url">URL:</label>
<input type="text" class="form-control" id="url" placeholder="Enter URL" size="50">
</div>
<button type="button" class="btn btn-primary" onclick="fetchRSS()">情報取得</button>
</form>
<br>
<div id="result"></div>
</div>
</body>
</html>