将一维数组输出到类别和子类别html列表中

var data = [
  { category: '类别1', subcategory: '子类别1' },
  { category: '类别1', subcategory: '子类别2' },
  { category: '类别2', subcategory: '子类别3' },
  { category: '类别2', subcategory: '子类别4' },
  { category: '类别3', subcategory: '子类别5' }
];

var rootUl = document.createElement('ul');

// 用于存储类别<ul>元素的对象
var categoryUlMap = {};

for (var i = 0; i < data.length; i++) {
  var category = data[i].category;
  var subcategory = data[i].subcategory;

  // 如果类别<ul>元素不存在，则创建并添加到根节点下
  if (!categoryUlMap[category]) {
    var categoryLi = document.createElement('li');
    categoryLi.textContent = category;

    var subcategoryUl = document.createElement('ul');
    categoryLi.appendChild(subcategoryUl);

    rootUl.appendChild(categoryLi);

    categoryUlMap[category] = subcategoryUl;
  }

  // 创建子类别<li>元素，并添加到对应的类别<ul>下
  var subcategoryLi = document.createElement('li');
  subcategoryLi.textContent = subcategory;

  categoryUlMap[category].appendChild(subcategoryLi);
}

// 将根节点添加到页面中的某个容器元素
var container = document.getElementById('container');
container.appendChild(rootUl);

<div id="container"></div>