嵌套数组到HTML列表

function nestedArrayToHTMLList(arr) {
  let list = document.createElement('ul');
  for (let i = 0; i < arr.length; i++) {
    let listItem = document.createElement('li');
    if (Array.isArray(arr[i])) {
      listItem.appendChild(nestedArrayToHTMLList(arr[i]));
    } else {
      listItem.textContent = arr[i];
    }
    list.appendChild(listItem);
  }
  return list;
}

let nestedArray = [
  'Item 1',
  'Item 2',
  [
    'Subitem 1',
    'Subitem 2',
    [
      'Sub-subitem 1',
      'Sub-subitem 2'
    ]
  ],
  'Item 3'
];

let htmlList = nestedArrayToHTMLList(nestedArray);
document.body.appendChild(htmlList);