js数组格式转换问题

Question

如何将上面这个数据，转换成下面这种，初学者，表示好难，还请各位老哥答疑解惑
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Answer 1

编辑一下，建议题主下次贴代码，不要放截图，谢谢。

arr.reduce((acc, cur) => {
  const { year, month } = cur;

  let targetYearObj = acc.find((item) => item.year === year);
  if (!targetYearObj) {
    targetYearObj = { year, list: [] };
    acc.push(targetYearObj);
  }

  let targetMonthObj = targetYearObj.list.find((item) => item.month === month);
  if (!targetMonthObj) {
    targetMonthObj = { month, children: [] };
    targetYearObj.list.push(targetMonthObj);
  };

  targetMonthObj.children.push(cur);
  return acc;
}, []);

Answer 2

var list = [
    {year: 2020, month: 8, title: 'sdfsdfadfs'},
    {year: 2020, month: 8, title: '123213'},
    {year: 2020, month: 8, title: '45645654'},
    {year: 2020, month: 8, title: '67876'},
    {year: 2020, month: 8, title: '09'},
    {year: 2020, month: 7, title: '0000'},
    {year: 2020, month: 7, title: 'asdf234'},
    {year: 2020, month: 6, title: '23432'},
    {year: 2019, month: 8, title: 'sdfsdfadfs'},
];

function groupBy(key, list, childKey='list') {
    return Object.entries(list.reduce((res, v) => {
       const group = res[ v[key] ];
       if(group) group.push(v);
       else res[v[key]] = [v];
       return res;
    }, {})).map(([value, group]) => ({[key]: value, [childKey]: group}));
}

groupBy('year', list).map(group => ({year: group.year, list: groupBy('month', group.list, 'children')}))

输出并不是按年降序的。如果有要求顺序可以加一个sort