How to fill dates in an array containing range of dates?

Question

I have an array of dates containing a count value. e.g.

[
  {
    "date": "2014-11-11T08:00:00.000Z",
    "count": 8
  },
  {
    "date": "2014-11-13T08:00:00.000Z",
    "count": 4
  }
  {
    "date": "2014-11-16T08:00:00.000Z",
    "count": 4
  }
]

How do I fill in the missing dates with count = 0, to produce the following in javascript:

[
  {
    "date": "2014-11-11T08:00:00.000Z",
    "count": 8
  },
  {
    "date": "2014-11-12T08:00:00.000Z",
    "count": 0
  },
  {
    "date": "2014-11-13T08:00:00.000Z",
    "count": 4
  },
  ...
]

Nathan Fisher · Accepted Answer · 2014-10-23 00:42:05Z

2

as you appear to be using momentjs

the first thing that came to mind was use the moment().add(number, units) and moment().diff(input, units, asFloat)

something like

var data = [
  {
    "date": "2014-11-11T08:00:00.000Z",
    "count": 8
  }, {
    "date": "2014-11-16T08:00:00.000Z",
    "count": 4
  }
];

var startDate = moment(data[0].date);
var endDate = moment(data[1].date);

var days = endDate.diff(startDate, 'd', false);
alert(days);
for (var i = 1; i < days; i++) {
  data.splice(i,0, {"date" : startDate.add(1, 'd').toISOString(), 'count': 0  })
}


for (var i = 0; i < data.length; i++) {
 alert(data[i].date);
}

<script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.8.3/moment.min.js"></script>

edited Oct 23, 2014 at 0:42

answered Oct 23, 2014 at 0:32

Nathan Fisher

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1 Comment

tgordon18 Over a year ago

You should change alert to console.log so that running the code snippet doesn't result in 7 alerts

dug · Accepted Answer · 2014-10-23 00:36:14Z

1

Try this:

var arr = [
    {
        "date": "2014-11-11T08:00:00.000Z",
        "count": 8
    },
    {
        "date": "2014-11-16T08:00:00.000Z",
        "count": 4
    }
];

function fillDates(start, end) {
    var output = [start];
    var date = new Date(start.date);
    var endDate = new Date(end.date);

    do {
        output.push({
            "date": date.toISOString(),
            "count": 0
        });
        date = new Date(date.getTime());
        date.setDate(date.getDate() + 1);
    } while (date < endDate);

    output.push(end);
    return output;
}

var start = arr[0];
var end = arr[1];
fillDates(start, end);

edited Oct 23, 2014 at 0:36

answered Oct 23, 2014 at 0:29

dug

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2 Comments

user4172076 Over a year ago

But what if there's a value in the middle? for example on the 13th? How can I check if there is data on the 13th or not before doing the push. Thanks.

dug Over a year ago

Make multiple calls to fillDates() and concatenate the results. You'll want to modify the function or the concatenations so the intermediate values only appear once in the result.

codeBelt · Accepted Answer · 2018-10-23 20:26:28Z

const models = [
    {
        date: '2018-10-17',
        value: 3,
    },
    {
        date: '2018-10-20',
        value: 4,
    },
    {
        date: '2018-10-21',
        value: 5,
    },
    {
        date: '2018-10-27',
        value: 6,
    },
];

const filledInDates = models.reduce((newArray, currentModel, index, originalArray) => {
    const nextModel = originalArray[index + 1];

    if (nextModel) {
        const currentDate = moment(currentModel.date);
        const daysBetween = moment(nextModel.date).diff(currentDate, 'days');

        const fillerDates = Array.from({length: daysBetween - 1}, (value, dayIndex) => {
            return {
                value: currentModel.value,
                date: moment(currentDate).add(dayIndex + 1, 'days').format('YYYY-MM-DD'),
            };
        });

        newArray.push(currentModel, ...fillerDates);
    } else {
        newArray.push(currentModel);
    }

    return newArray;
}, []);

console.log(filledInDates);

Output:

[
    {value:3, date:"2018-10-17"},
    {value:3, date:"2018-10-18"},
    {value:3, date:"2018-10-19"},
    {value:4, date:"2018-10-20"},
    {value:5, date:"2018-10-21"},
    {value:5, date:"2018-10-22"},
    {value:5, date:"2018-10-23"},
    {value:5, date:"2018-10-24"},
    {value:5, date:"2018-10-25"},
    {value:5, date:"2018-10-26"},
    {value:6, date:"2018-10-27"}
]

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