Javascript - Get Previous Months Date

Question

If i have a variable that returns a date, in the format of dd MMM yyyy, so 28 Aug 2014, how can i get the date of the previous month.

I can modify the month via:

$scope.DateMapping = function (months) {

    var myVariable = "28 Aug 2014"
    var makeDate = new Date(myVariable);
    prev = new Date(makeDate.getFullYear(), makeDate.getMonth()+1, 1);

});

Essentially, this is adding one to the Month.. But how can i account for years, so if the current date is 12 Dec 2014, the previous would be 12 Jan 2013?

My application is using AngularJS can make use of filters.

UPDATE:

    var myVariable = "28 Aug 2014"
    var makeDate = new Date(myVariable);
    var prev = new Date(makeDate.getFullYear(), makeDate.getMonth()+1, makeDate.getMonth());

    console.log(myVariable)
    console.log(makeDate)
    console.log(prev)

Output:

    28 Aug 2014
    Thu Aug 28 2014 00:00:00 GMT+0100 (GMT Standard Time)
    Mon Sep 01 2014 00:00:00 GMT+0100 (GMT Standard Time)

How comes although the month has incremented, the day is showing as 01 instead of 28?

Solution 1

var myVariable = "28 Aug 2014"
var makeDate = new Date(myVariable);
makeDate = new Date(makeDate.setMonth(makeDate.getMonth() - 1));

Update:

A shorter version:

var myVariable = "28 Aug 2014"
var makeDate = new Date(myVariable);

console.log('Original date: ', makeDate.toString());

makeDate.setMonth(makeDate.getMonth() - 1);

console.log('After subtracting a month: ', makeDate.toString());

Update 2:

If you don't want to deal with corner cases just use moment.js. Native JavaScript API for Date is bad.

Solution 2

Just subtract the number of months from the month parameter and don't worry if the value is going to be negative. It will be handled correctly.

new Date(2014, 0, 1) // 1st Jan 2014
new Date(2014, -1, 1) // 1st Dec 2013

Solution 3

For all date related activities I recommend using the moment.js library and as you are using AngularJS there is a library for this: https://github.com/urish/angular-moment.

Take a look at the moment.js documentation and you will see it makes it much easier to manipulate dates in JavaScript: http://momentjs.com/docs/#/get-set/month/

You will easily be able to solve the problem you are facing, for example:

var now = moment('01/01/2014').subtract(1, 'months').format('DD/MM/YYYY');

now would then equal 01/12/2013.

Solution 4

You could use moment.js subtract function for this.

var day = moment("2014-08-28");
day.subtract(1, 'months');

Solution 5

var myVariable = "28 Aug 2014"
var makeDate = new Date(myVariable);

console.log('Original date: ', makeDate.toString());

makeDate.setMonth(makeDate.getMonth() - 6);

console.log('After subtracting half year: ', makeDate.toString());

View more solutions

Comments

[Oam Psy]

Thanks, ideally i would like to achieve this without another library.. Please see my updated. I expected Angular to do something like this very easily.

[Oam Psy]

@Dimitry - can i minus the day by 1 too? e.g. makeDate = new Date(makeDate.setMonth(makeDate.getMonth() - 1), makeDate.setDate(makeDate.getDate() - 1));

[Dmitry]

makeDate = new Date(new Date(makeDate.setMonth(makeDate.getMonth() - 1)).setDate(makeDate.getDate() - 1));

[Asif Mehmood]

Does it work if i say i have date "31 Aug 2014" and i want next months date. Wouldn't this logic give error if i add one month because September does not have 31st day (just asking, if that happens). I guess it would take me to 1st, October, instead of some date that is present in September.

[sabithpocker]

Moment is no longer recommended until its ready for treeshaking. date-fns is recommended for Angular5. (my personal recommendation)

[smac89]

I hope people are reading the above code correctly, the second one does not mean "subtract one month from the current date", it actually means go to month 0 (Jan) and subtract one month, thus going back to December of the previous year. Pay careful attention to the commented part beside it

[Serkan KONAKCI]

This method will not work for "Fri Mar 29 2019" // -> will return Fri Mar 01 2019

[Dmitry]

@CharinduEdirisooriya yep, does not looks like there is a simple way to do it without moment.js

[Elinoter99]

@Dmitry newDate.setDate( date.getDate() - 31 ); console.log(newDate); return newDate;

[Dmitry]

@CharinduEdirisooriya this is kind of works, but if you use it on say '28 Mar 2014' you'll get '25 Feb 2014'. However in moment.js it works as intended.