Finally let's see the code to be inserted at the bottom of the JSP page to initialize and use the component to select a folder from the Liferay Document Library.

<aui:script use="liferay-dl-util">
    new Liferay.DLUtil.FolderSelector({
        /* HTML container name set above */
        container: '#<portlet:namespace/>folderSelector',
        /* CSS selector to identify the field to fill in the folderId */
        hiddenInput: '#<portlet:namespace/>folderId',
        /* events provided by the widget */
        on: {
            click: function(button, event) {
                /*
                 * Function invoked at the button click, before the dialog opens; insert here your code if needed
                 */
            },
            select: function(folderId, folderName, isSupportMetaData, isSupportSocial) {
                /*
                 * Function invoked "after" file selection; insert here your code in case you need informations
                 * other than simple the document UUID
                 */

                // this sample code only display, inside the textarea above, all the informations provided by
                // the widget
                var area = A.one('#<portlet:namespace/>folderArea');
                var msg = 'FolderId: ' + folderId + '\n' +
                          'FolderName: ' + folderName + '\n' +
                          'IsSupportMetaData: ' + isSupportMetaData + '\n' +
                          'IsSupportSocial: ' + isSupportSocial;
                area.val(msg);
            }
        }
    }).render();
</aui:script>