function opennamu_do_editor_preview() {
    var input = document.querySelector('#opennamu_edit_textarea');
    if (input !== null) {
        fetch("/api/w/test/doc_tool/preview", {
            method: 'POST',
            headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
            body: new URLSearchParams({
                'data': input.value,
            })
        }).then(function (res) {
            return res.json();
        }).then(function (text) {
            var preview = document.querySelector('#opennamu_preview_area');
            if (preview !== null) {
                preview.innerHTML = text.data;
                eval(text.js_data);
            }
        });
    }
}