JavaScript:如何根据字段对数组中的相同字段进行添加和排序？

var arr = [
  { name: 'John', age: 25 },
  { name: 'Jane', age: 30 },
  { name: 'Bob', age: 20 },
  { name: 'Alice', age: 25 }
];

arr.sort(function(a, b) {
  if (a.age < b.age) {
    return -1;
  }
  if (a.age > b.age) {
    return 1;
  }
  return 0;
});

arr.reduce(function(prev, curr) {
  if (prev.age === curr.age) {
    prev.names.push(curr.name);
  } else {
    curr.names = [curr.name];
    prev = curr;
  }
  return prev;
});

var arr = [
  { name: 'John', age: 25 },
  { name: 'Jane', age: 30 },
  { name: 'Bob', age: 20 },
  { name: 'Alice', age: 25 }
];

arr.sort(function(a, b) {
  if (a.age < b.age) {
    return -1;
  }
  if (a.age > b.age) {
    return 1;
  }
  return 0;
});

arr.reduce(function(prev, curr) {
  if (prev.age === curr.age) {
    prev.names.push(curr.name);
  } else {
    curr.names = [curr.name];
    prev = curr;
  }
  return prev;
});

console.log(arr);