fetch.html

<script type="text/javascript">
    document.getElementById('author').addEventListener("click", () => {
        fetch('/test2')
            .then(function (response) {
                return response.text()
            }).then(function (content) {
            let result = document.getElementById('result');
            // Convert the HTML string into a document object
            var parser = new DOMParser();
            var html = parser.parseFromString(content, 'text/html');
            result.append(html.getElementById('insert'));
        });
    });
    document.getElementById('author').addEventListener("click", () => {
        fetch('/authors')
            .then(function (response) {
                return response.json();
            }).then(function (json) {
                let result = document.getElementById('result');

                json.forEach(author => {
                    let li = document.createElement('li').innerHTML = author.name;
                    result.append(li);
                });
            });
    });
</script>