Moment JS start and end of given month

Question

I need to calculate a JS date given year=2014 and month=9 (September 2014).

I tried this:

var moment = require('moment');
var startDate = moment( year+'-'+month+'-'+01 + ' 00:00:00' );
            var endDate = startDate.endOf('month');
            console.log(startDate.toDate());
            console.log(endDate.toDate());

Both of logs show:

Tue Sep 30 2014 23:59:59 GMT+0200 (CEST)
Tue Sep 30 2014 23:59:59 GMT+0200 (CEST)

End date is correct but... why the start date is not?

Answer 1

var d = new moment();
var startMonth = d.clone().startOf('month');
var endMonth = d.clone().endOf('month');
console.log(startMonth, endMonth);

doc

Answer 2

Try the following code:

const moment=require('moment');
console.log("startDate=>",moment().startOf('month').format("YYYY-DD-MM"));
console.log("endDate=>",moment().endOf('month').format("YYYY-DD-MM"));

Answer 3

The following code should work:

$('#reportrange').daterangepicker({
                startDate: start,
                endDate: end,
                ranges: {
                    'Hoy': [moment(), moment()],
                    'Ayer': [moment().subtract(1, 'days'), moment().subtract(1, 'days')],
                    'Ultimos 7 dias': [moment().subtract(6, 'days'), moment()],
                    'Ultimos 30 dias': [moment().subtract(29, 'days'), moment()],
                    'Mes actual': [moment().startOf('month'), moment().endOf('month')],
                    'Ultimo mes': [moment().subtract(1, 'month').startOf('month'), moment().subtract(1, 'month').endOf('month')],
                    'Enero': [moment().month(0).startOf('month') , moment().month(0).endOf('month')],
                    'Febrero': [moment().month(1).startOf('month') , moment().month(1).endOf('month')],
                    'Marzo': [moment().month(2).startOf('month') , moment().month(2).endOf('month')],
                    'Abril': [moment().month(3).startOf('month') , moment().month(3).endOf('month')],
                    'Mayo': [moment().month(4).startOf('month') , moment().month(4).endOf('month')],
                    'Junio': [moment().month(5).startOf('month') , moment().month(5).endOf('month')],
                    'Julio': [moment().month(6).startOf('month') , moment().month(6).endOf('month')],
                    'Agosto': [moment().month(7).startOf('month') , moment().month(7).endOf('month')],
                    'Septiembre': [moment().month(8).startOf('month') , moment().month(8).endOf('month')],
                    'Octubre': [moment().month(9).startOf('month') , moment().month(9).endOf('month')],
                    'Noviembre': [moment().month(10).startOf('month') , moment().month(10).endOf('month')],
                    'Diciembre': [moment().month(11).startOf('month') , moment().month(11).endOf('month')]
                }
            }, cb);

Answer 4

When you use .endOf() you are mutating the object it's called on, so startDate becomes Sep 30

You should use .clone() to make a copy of it instead of changing it

var startDate = moment(year + '-' + month + '-' + 01 + ' 00:00:00');
            var endDate = startDate.clone().endOf('month');
            console.log(startDate.toDate());
            console.log(endDate.toDate());

Mon Sep 01 2014 00:00:00 GMT+0700 (ICT) 
Tue Sep 30 2014 23:59:59 GMT+0700 (ICT) 

Answer 5

const year = 2014;
const month = 09;

// months start at index 0 in momentjs, so we subtract 1
const startDate = moment([year, month - 1, 01]).format("YYYY-MM-DD");

// get the number of days for this month
const daysInMonth = moment(startDate).daysInMonth();

// we are adding the days in this month to the start date (minus the first day)
const endDate = moment(startDate).add(daysInMonth - 1, 'days').format("YYYY-MM-DD");

console.log(`start date: ${startDate}`);
console.log(`end date:   ${endDate}`);

<script
src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.20.1/moment.min.js">
</script>

Answer 6

That's because endOf mutates the original value.

Relevant quote:

Mutates the original moment by setting it to the end of a unit of time.

Here's an example function that gives you the output you want:

function getMonthDateRange(year, month) {
    var moment = require('moment');

    // month in moment is 0 based, so 9 is actually october, subtract 1 to compensate
    // array is 'year', 'month', 'day', etc
    var startDate = moment([year, month - 1]);

    // Clone the value before .endOf()
    var endDate = moment(startDate).endOf('month');

    // just for demonstration:
    console.log(startDate.toDate());
    console.log(endDate.toDate());

    // make sure to call toDate() for plain JavaScript date type
    return { start: startDate, end: endDate };
}

References:

• endOf()
• clone()
• Date from object