how to group date array by month in javascript
https://stackoverflow.com/questions/14446511/most-efficient-method-to-groupby-on-an-array-of-objects
function groupBy(list, keyGetter) {
const map = new Map();
list.forEach((item) => {
const key = keyGetter(item);
const collection = map.get(key);
if (!collection) {
map.set(key, [item]);
} else {
collection.push(item);
}
});
return map;
}
// example usage
const pets = [
{type:"Dog", name:"Spot"},
{type:"Cat", name:"Tiger"},
{type:"Dog", name:"Rover"},
{type:"Cat", name:"Leo"}
];
const grouped = groupBy(pets, pet => pet.type);
console.log(grouped.get("Dog"));
// [{type:"Dog", name:"Spot"}, {type:"Dog", name:"Rover"}]
console.log(grouped.get("Cat"));
// [{type:"Cat", name:"Tiger"}, {type:"Cat", name:"Leo"}]
https://stackoverflow.com/questions/41888837/js-group-by-month-of-date-values-objects-in-an-array
const dates = [
{date: "2017-01-01", num: "2"},
{date: "2017-01-02", num: "3"},
{date: "2017-02-04", num: "6"},
{date: "2017-02-05", num: "15"}
],
let groupKey = 0;
groups = dates.reduce(function (r, o) {
var m = o.date.split(('-'))[1];
(r[m])? r[m].data.push(o) : r[m] = {group: String(groupKey++), data: [o]};
return r;
}, {});
const result = Object.keys(groups).map(k => groups[k]);
console.log(result);
OK
const json = [
{
"id": 191701,
"productId": 13602,
"activityEventId": 1623852,
"ticketCategoryId": 5246618,
"ticketGroupId": 11798619,
"start": 1585670400000,
"end": 1585670400000,
"ticketsNumber": 100,
"lowPrice": 127.00,
"status": 0,
"priceLowest": false,
"hasTicket": true,
"availableNumbers": [
1,
2,
3,
4,
5,
6
],
order: "C"
},
{
"id": 191837,
"productId": 13602,
"activityEventId": 1623896,
"ticketCategoryId": 5246754,
"ticketGroupId": 11798755,
"start": 1585497600000,
"end": 1585497600000,
"ticketsNumber": 100,
"lowPrice": 127.00,
"status": 0,
"priceLowest": false,
"hasTicket": true,
"availableNumbers": [
1,
2,
3,
4,
5,
6
],
order: "A"
},
{
"id": 191812,
"productId": 13602,
"activityEventId": 1623891,
"ticketCategoryId": 5246729,
"ticketGroupId": 11798730,
"start": 1585584000000,
"end": 1585584000000,
"ticketsNumber": 100,
"lowPrice": 127.00,
"status": 0,
"priceLowest": false,
"hasTicket": true,
"availableNumbers": [
1,
2,
3,
4,
5,
6
],
order: "B"
},
];
const sortArray = json.sort((a, b) => a.start > b.start ? 1 : -1);
// asc order 升序
const calendarArray = sortArray.map(obj => {
const date = new Date(obj.start);
const year = date.getFullYear();
const month = date.getMonth() + 1;
return {
year,
month,
...obj,
};
});
// group date by month / year
const groupArrayByKey = (items, key) => items.reduce(
(result, item) => ({
...result,
[item[key]]: [
...(result[item[key]] || []),
item,
],
}),
{},
);
const groupArray = groupArrayByKey(calendarArray, `month`);
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