create new array of object with keys from data, base on array of object with condition-CodePudding

const October = [
  {
    event_category: 'EVENT',
    date: '2022-10-02',
    detail: 'event',
  },
  {
    event_category: 'TASK',
    date: '2022-10-03',
    detail: 'task',
  },
  {
    event_category: 'EVENT',
    date: '2022-10-04',
    detail: 'event 1',
  },
  {
    event_category: 'TASK',
    date: '2022-10-04',
    detail: 'task 1',
  },
  {
    event_category: 'TASK',
    date: '2022-10-04',
    detail: 'task 2',
  },
];

is there a method with map or reduce to create new array of object like this. i have try method with object assign etc.. cant solve it.

the result i want.

const newOct = [
  {
    '2022-10-02': {
      event_category: 'EVENT',
      date: '2022-10-02',
    },
    '2022-10-03': {
      event_category: 'TASK',
      date: '2022-10-03',
    },
    '2022-10-04': {
      event_category: 'TASK_EVENT',
      date: '2022-10-04',
    },
  },
];

CodePudding user response：

You achieve it by using following code

const October = [
    {
        event_category: 'EVENT',
        date: '2022-10-02',
        detail: 'event',
    },
    {
        event_category: 'TASK',
        date: '2022-10-03',
        detail: 'task',
    },
    {
        event_category: 'EVENT',
        date: '2022-10-04',
        detail: 'event 1',
    },
    {
        event_category: 'TASK',
        date: '2022-10-04',
        detail: 'task 1',
    },
    {
        event_category: 'TASK',
        date: '2022-10-04',
        detail: 'task 2',
    },
];

function onlyUnique(value, index, self) {
    return self.indexOf(value) === index;
}

let newOct = [{}];
let dates = October.map(item => item.date);
dates = dates.filter(onlyUnique);

for (let date of dates) {
    let event_category = ''; 
    for (let item of October) {
        if (item.date === date) {
            event_category = event_category ? event_category.includes(item.event_category) ? event_category : event_category   "_"   item.event_category : item.event_category;
        }
    }
    newOct[0][date] = { event_category, date };
}
console.log('newOct: ', newOct);