按年份和月份对数组进行分组

Question

我想按年份和月份对一个包含事件的数组进行分组。我的数据如下：

const events = [
{
name: "event 1",
year: 2021,
month: 1,
},
{
name: "event 2",
year: 2021,
month: 9,
},
{
name: "event 3",
year: 2021,
month: 1,
},
{
name: "event 4",
year: 2022,
month: 7,
},
]

我预期的结果应该是这样的：

[
{
year: 2021,
month: 1,
events: [
{
name: "event 1"
},
{
name: "event 3"
}
]
},
{
year: 2021,
month: 9,
events: [
{
name: "event 2"
}
]
}
]

做到这一点的最佳方法是什么？我找到了几个stackoverflow帖子来根据数组的键值对其进行分组，但这不是我想要的。

const groupBy = (array, key) => {
return array.reduce((result, currentValue) => {
// If an array already present for key, push it to the array. Else create an array and push the object
(result[currentValue[key]] = result[currentValue[key]] || []).push(currentValue);
// Return the current iteration `result` value, this will be taken as next iteration `result` value and accumulate
return result;
}, {}); // empty object is the initial value for result object
};
const groupedByYear = groupBy(events, 'year');

Answer 1

您可以使用reduce和Object.values执行此操作

const events = [
{
name: "event 1",
year: 2021,
month: 1,
},
{
name: "event 2",
year: 2021,
month: 9,
},
{
name: "event 3",
year: 2021,
month: 1,
},
];
const result = Object.values(events.reduce( (acc,evt) => {
const key = `${evt.year}-${evt.month}`;
if(!acc[key]) {
acc[key] = {year: evt.year, month: evt.month, events:[]}
}
acc[key].events.push( {name:evt.name} );
return acc;
},{}));
console.log(result);

Answer 2

您可以采用动态方法，使用所需属性的组合键进行分组。

然后移除松鸡的所有关键点，并推送一个没有多余属性的新对象。

const
events = [{ name: "event 1", year: 2021, month: 1 }, { name: "event 2", year: 2021, month: 9 }, { name: "event 3",  year: 2021, month: 1 }],
keys = ['year', 'month'],
result = Object.values(events.reduce((r, o) => {
let value,
key = keys.map(k => o[k]).join('|');
if (!r[key]) r[key] = { ...Object.fromEntries(keys.map(k => [k, o[k]])), events: [] };

r[key].events.push(keys.reduce((t, k) => (({ [k]: value, ...t } = t), t), o));
return r;
}, {}));
console.log(result);

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