index.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>CloudFlare Worker</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <script src="main.js"></script>
    <script>
    function goFetch() {
        var url = document.getElementById('url').value;
        return (async () => {
            let response = await fetch(url);
            let json = await response.text();

            document.getElementById('response').value = json;
        })();
    }
    </script>
</head>
<body>
    CloudFlare Worker:
    URL to Fetch: <input type="text" id="url" value="/route/1" /> <button type="submit" id="btnGo" onclick="goFetch()">Go</button>
    <br/><br/>
    <textarea id="response" rows="8" cols="60"></textarea>
</body>
</html>