landing-pages/src/js/tocTree.js

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

Array.from(document.querySelectorAll(".toctree ul")).forEach((listElement) => {
  const siblingsLinks = Array.from(listElement.parentNode.children).filter((d) => d.tagName === "A");
  siblingsLinks.forEach((linkElement) => {
    const expandElement = document.createElement("span");
    expandElement.classList.add("toctree-expand");
    linkElement.insertBefore(expandElement, linkElement.firstChild);
  });
});