Textarea Merge Tag

jQuery(document).ready(function($) {
    tinymce.PluginManager.add('custom_mergetag_plugin', function(editor) {
        var tagList = ['first_name','last_name','event','event_slug','weeks_away','start_date','start_time','end_date','end_time','linens','schedule','lodging', 'facebook','instagram','linked_event','linked_event_link','full_dates','4_weeks_out','2_weeks_out'];
        function buildList() {
            var list = '';
            tagList.forEach(function(tag) {
                list += '<li data-mergetag="' + tag + '">' + tag.charAt(0).toUpperCase() + tag.slice(1) + '</li>';
            });
            return list;
        }

        editor.addButton('custom_mergetag_button', {
            text: ' Merge Tag',
            icon: 'upload',
            onclick: function() {
                var listHtml = '<ul id="custom-mergetag-list">' + buildList() + '</ul>';
                editor.windowManager.open({
                    title: 'Select a Merge Tag',
                    body: [{
                        type: 'container',
                        html: listHtml,
                        onclick: function(e) {
                            if (e.target.nodeName === 'LI') {
                                var tag = e.target.getAttribute('data-mergetag');
                                editor.insertContent('{{' + tag + '}}');
                                editor.windowManager.close();
                            }
                        }
                    }]
                });
            }
        });
    });

    if (typeof tinymce !== 'undefined') {
        tinymce.init({
            selector: '.gform_wrapper textarea',
			plugins: "image link lists media custom_mergetag_plugin textcolor",
            toolbar: ['undo redo | formatselect | bold italic underline strikethrough | fontfamily fontsize blocks | alignleft aligncenter alignright alignjustify | outdent indent |  numlist bullist | forecolor backcolor removeformat |  ltr rtl | custom_mergetag_button'],
			branding: false,
            menubar: true
        });
    }
});