var people = [
  { name: '牛油1号', id: 1, age: 20 },
  { name: '牛油2号', id: 2, age: 21 },
  { name: '牛油3号', id: 3, age: 19 },
]
var ul = document.querySelector('ul');
// 补全代码
ul.innerHTML = people.map(p => '<li>' + p.name + p.age + '岁</li><br>').join('')