text: /* globals jQuery */
  /**
   * Adds context menu functionality.
   * @module contextmenu
   * @license Apache-2.0
   * @author Adam Bender
   */
  // Dependencies:
  // 1) jQuery (for dom injection of context menus)
  
  const $ = jQuery;
  
  let contextMenuExtensions = {};
  
  /**
   * Signature depends on what the user adds; in the case of our uses with
   * SVGEditor, no parameters are passed nor anything expected for a return.
   * @callback module:contextmenu.MenuItemAction
   * @param {...args} args
   * @returns {any}
  */
  
  /**
  * @typedef {PlainObject} module:contextmenu.MenuItem
  * @property {string} id
  * @property {string} label
  * @property {module:contextmenu.MenuItemAction} action
  */
  
  /**
  * @param {module:contextmenu.MenuItem} menuItem
  * @returns {boolean}
  */
  const menuItemIsValid = function (menuItem) {
    return menuItem && menuItem.id && menuItem.label && menuItem.action && typeof menuItem.action === 'function';
  };
  
  /**
  * @function module:contextmenu.add
  * @param {module:contextmenu.MenuItem} menuItem
  * @throws {Error|TypeError}
  * @returns {void}
  */
  export const add = function (menuItem) {
    // menuItem: {id, label, shortcut, action}
    if (!menuItemIsValid(menuItem)) {
      throw new TypeError(
        'Menu items must be defined and have at least properties: ' +
        'id, label, action, where action must be a function'
      );
    }
    if (menuItem.id in contextMenuExtensions) {
      throw new Error('Cannot add extension "' + menuItem.id + '", an extension by that name already exists"');
    }
    // Register menuItem action, see below for deferred menu dom injection
    console.log('Registered contextmenu item: {id:' + menuItem.id + ', label:' + menuItem.label + '}'); // eslint-disable-line no-console
    contextMenuExtensions[menuItem.id] = menuItem;
    // TODO: Need to consider how to handle custom enable/disable behavior
  };
  
  /**
  * @function module:contextmenu.hasCustomHandler
  * @param {string} handlerKey
  * @returns {boolean}
  */
  export const hasCustomHandler = function (handlerKey) {
    return Boolean(contextMenuExtensions[handlerKey]);
  };
  
  /**
  * @function module:contextmenu.getCustomHandler
  * @param {string} handlerKey
  * @returns {module:contextmenu.MenuItemAction}
  */
  export const getCustomHandler = function (handlerKey) {
    return contextMenuExtensions[handlerKey].action;
  };
  
  /**
  * @param {module:contextmenu.MenuItem} menuItem
  * @returns {void}
  */
  const injectExtendedContextMenuItemIntoDom = function (menuItem) {
    if (!Object.keys(contextMenuExtensions).length) {
      // all menuItems appear at the bottom of the menu in their own container.
      // if this is the first extension menu we need to add the separator.
      $('#cmenu_canvas').append("<li class='separator'>");
    }
    const shortcut = menuItem.shortcut || '';
    $('#cmenu_canvas').append("<li class='disabled'><a href='#" + menuItem.id + "'>" +
      menuItem.label + "<span class='shortcut'>" +
      shortcut + '</span></a></li>');
  };
  
  /**
  * @function module:contextmenu.injectExtendedContextMenuItemsIntoDom
  * @returns {void}
  */
  export const injectExtendedContextMenuItemsIntoDom = function () {
    Object.values(contextMenuExtensions).forEach((menuItem) => {
      injectExtendedContextMenuItemIntoDom(menuItem);
    });
  };
  /**
  * @function module:contextmenu.resetCustomMenus
  * @returns {void}
  */
  export const resetCustomMenus = function () { contextMenuExtensions = {}; };
  