collection of items with varying dates

Question

collection of items with varying dates

I have an array of objects, each containing a date. My goal is to create a new array of objects grouped by weeks. Here is an example code snippet:

const data = [
  {
    "id": 1,
    "status": 1,
    "createdAt": "2022-05-01T08:28:36.284Z"
  },
  {
    "id": 2,
    "status": 2,
    "createdAt": "2022-05-02T07:17:11.724Z"
  },
  {
    "id": 3,
    "status": 3,
    "createdAt": "2022-05-10T07:03:44.465Z"
  },
  {
    "id": 4,
    "status": 3,
    "createdAt": "2022-05-11T16:17:48.863Z"
  }
]

The desired result is an array that groups objects by weeks as follows:

const newData = [
  {
    "week": 1,
    "status": 1,
    "status": 2
  },
  {
    "week": 2,
    "status": 3,
    "status": 3
  }]

Is this achievable? Can a property appear multiple times in the same object? Thank you

javascript arrays date object

Answer 1

Answer №1

To efficiently determine the week number for charting purposes, it is recommended to incorporate moment.js into your project. Here's a suitable approach:

const data = [
  {
    "id": 1,
    "status": 1,
    "createdAt": "2022-05-01T08:28:36.284Z"
  },
  {
    "id": 2,
    "status": 2,
    "createdAt": "2022-05-02T07:17:11.724Z"
  },
  {
    "id": 3,
    "status": 3,
    "createdAt": "2022-05-10T07:03:44.465Z"
  },
  {
    "id": 4,
    "status": 3,
    "createdAt": "2022-05-11T16:17:48.863Z"
  }
]
console.log(data.map(a => {
        return {
        status : a.status,
        week: moment(a.createdAt).week()
    }
    }
))

<script src="https://cdn.jsdelivr.net/momentjs/2.13.0/moment.min.js"></script>

The resulting array will display as follows:

[{
  status: 1,
  week: 19
}, {
  status: 2,
  week: 19
}, {
  status: 3,
  week: 20
}, {
  status: 3,
  week: 20
}]

Answer 2

To efficiently determine the week number for charting purposes, it is recommended to incorporate moment.js into your project. Here's a suitable approach:

const data = [
  {
    "id": 1,
    "status": 1,
    "createdAt": "2022-05-01T08:28:36.284Z"
  },
  {
    "id": 2,
    "status": 2,
    "createdAt": "2022-05-02T07:17:11.724Z"
  },
  {
    "id": 3,
    "status": 3,
    "createdAt": "2022-05-10T07:03:44.465Z"
  },
  {
    "id": 4,
    "status": 3,
    "createdAt": "2022-05-11T16:17:48.863Z"
  }
]
console.log(data.map(a => {
        return {
        status : a.status,
        week: moment(a.createdAt).week()
    }
    }
))

<script src="https://cdn.jsdelivr.net/momentjs/2.13.0/moment.min.js"></script>

The resulting array will display as follows:

[{
  status: 1,
  week: 19
}, {
  status: 2,
  week: 19
}, {
  status: 3,
  week: 20
}, {
  status: 3,
  week: 20
}]

Answer 3

Answer №2

When working with ECMAScript, it's important to remember that an object cannot have multiple properties with the same name. One way to handle this limitation is by using an array of objects structured like:

[{week: weekNo, statuses: [status0, status1, status2, …]}]

Since week numbers repeat every year, including the year in a format such as 2022W03 following ISO 8601 standards can help with parsing and sorting chronologically. This approach also accounts for transitioning dates across different years.

The combination of Array.prototype.reduce along with a function for calculating the week number can efficiently handle this task:

// Calculate ISO week number where week starts on Monday,
// first week contains 4 Jan or first Thursday of the year
function getWeekNumber(d) {
    let z = n => (n<10? '0' : '') + n; 
    d = new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
    d.setUTCDate(d.getUTCDate() + 4 - (d.getUTCDay()||7));
    var yearStart = new Date(Date.UTC(d.getUTCFullYear(),0,1));
    var weekNo = Math.ceil(( ( (d - yearStart) / 86400000) + 1)/7);
    return `${d.getUTCFullYear()}W${z(weekNo)}`;
}

function groupByWeek(data) {
  // Index pointer for week in array
  let index = {};
  let newData = data.reduce((acc, obj) => {
    let weekNo = getWeekNumber(new Date(obj.createdAt));
    if (!index[weekNo]) {
      index[weekNo] = acc.length;
      acc.push({week: weekNo, statuses: []});
    }
    acc[index[weekNo]].statuses.push(obj.status);
    return acc;
  }, []);
  // Sort by week number
  newData.sort((a, b) => a.week.localeCompare(b.week));
  return newData;
}

let data = [
  {"id": 1, "status": 1, "createdAt": "2022-05-01T08:28:36.284Z"},
  {"id": 2, "status": 2, "createdAt": "2022-05-02T07:17:11.724Z"},
  {"id": 3, "status": 3, "createdAt": "2022-05-10T07:03:44.465Z"},
  {"id": 4, "status": 3, "createdAt": "2022-05-11T16:17:48.863Z"},
  {"id": 5, "status": 1, "createdAt": "2023-01-05T08:28:36.284Z"},
];

console.log(groupByWeek(data))

Answer 4

When working with ECMAScript, it's important to remember that an object cannot have multiple properties with the same name. One way to handle this limitation is by using an array of objects structured like:

[{week: weekNo, statuses: [status0, status1, status2, …]}]

Since week numbers repeat every year, including the year in a format such as 2022W03 following ISO 8601 standards can help with parsing and sorting chronologically. This approach also accounts for transitioning dates across different years.

The combination of Array.prototype.reduce along with a function for calculating the week number can efficiently handle this task:

// Calculate ISO week number where week starts on Monday,
// first week contains 4 Jan or first Thursday of the year
function getWeekNumber(d) {
    let z = n => (n<10? '0' : '') + n; 
    d = new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
    d.setUTCDate(d.getUTCDate() + 4 - (d.getUTCDay()||7));
    var yearStart = new Date(Date.UTC(d.getUTCFullYear(),0,1));
    var weekNo = Math.ceil(( ( (d - yearStart) / 86400000) + 1)/7);
    return `${d.getUTCFullYear()}W${z(weekNo)}`;
}

function groupByWeek(data) {
  // Index pointer for week in array
  let index = {};
  let newData = data.reduce((acc, obj) => {
    let weekNo = getWeekNumber(new Date(obj.createdAt));
    if (!index[weekNo]) {
      index[weekNo] = acc.length;
      acc.push({week: weekNo, statuses: []});
    }
    acc[index[weekNo]].statuses.push(obj.status);
    return acc;
  }, []);
  // Sort by week number
  newData.sort((a, b) => a.week.localeCompare(b.week));
  return newData;
}

let data = [
  {"id": 1, "status": 1, "createdAt": "2022-05-01T08:28:36.284Z"},
  {"id": 2, "status": 2, "createdAt": "2022-05-02T07:17:11.724Z"},
  {"id": 3, "status": 3, "createdAt": "2022-05-10T07:03:44.465Z"},
  {"id": 4, "status": 3, "createdAt": "2022-05-11T16:17:48.863Z"},
  {"id": 5, "status": 1, "createdAt": "2023-01-05T08:28:36.284Z"},
];

console.log(groupByWeek(data))

Answer 5

Answer №3

To avoid having multiple properties with the same name in an object, it is recommended to store status values in an array.

const getWeekNumber = (date) => {
    date = formatDate(date);
    let firstDay = new Date(date.getFullYear(), 0, 1);
    let numberOfDays = Math.floor((date - firstDay) / (24*60*60*1000));
    return Math.ceil((date.getDay() + 1 + numberOfDays) / 7);
}

const formatDate = (date) => new Date(Date.parse(date));

const groupBy = (arr, key) => arr.reduce((result, item) => {
        (result[item[key]] = result[item[key]] || []).push(item);
        return result;
    }, {});

const formattedData = data.map(d => ({...d, week: getWeekNumber(d.createdAt)}));                                       // calculate week number
const groupedData = groupBy(formattedData, 'week');                                                                 // group data by week property's value
const result = Object.values(groupedData).map(arr => ({week: arr[0].week, status: arr.map(d => d.status)}));    // format result

console.log(result);

// Output
// [
//     { "week": 18, "status": [1, 2] },
//     { "week": 19, "status": [3] },
//     { "week": 20, "status": [3] }
// ]

Answer 6

To avoid having multiple properties with the same name in an object, it is recommended to store status values in an array.

const getWeekNumber = (date) => {
    date = formatDate(date);
    let firstDay = new Date(date.getFullYear(), 0, 1);
    let numberOfDays = Math.floor((date - firstDay) / (24*60*60*1000));
    return Math.ceil((date.getDay() + 1 + numberOfDays) / 7);
}

const formatDate = (date) => new Date(Date.parse(date));

const groupBy = (arr, key) => arr.reduce((result, item) => {
        (result[item[key]] = result[item[key]] || []).push(item);
        return result;
    }, {});

const formattedData = data.map(d => ({...d, week: getWeekNumber(d.createdAt)}));                                       // calculate week number
const groupedData = groupBy(formattedData, 'week');                                                                 // group data by week property's value
const result = Object.values(groupedData).map(arr => ({week: arr[0].week, status: arr.map(d => d.status)}));    // format result

console.log(result);

// Output
// [
//     { "week": 18, "status": [1, 2] },
//     { "week": 19, "status": [3] },
//     { "week": 20, "status": [3] }
// ]

collection of items with varying dates

Answer №1

Answer №2

Answer №3

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