如何对数组进行排序，同时在Javascript中加载页面时选择一个项

var numbers = [5, 1, 3, 2, 4];
numbers.sort(function(a, b) {
  return a - b;
});
console.log(numbers); // 输出 [1, 2, 3, 4, 5]

var persons = [
  { name: 'Alice', age: 25 },
  { name: 'Bob', age: 20 },
  { name: 'Charlie', age: 30 }
];
persons.sort(function(a, b) {
  return a.age - b.age;
});
console.log(persons);
// 输出:
// [
//   { name: 'Bob', age: 20 },
//   { name: 'Alice', age: 25 },
//   { name: 'Charlie', age: 30 }
// ]

window.addEventListener('load', function() {
  var selectElement = document.getElementById('mySelect');
  selectElement.selectedIndex = 2; // 选择第三个项
});