Javascript get timestamp of 1 month ago

Question

How do I get in unix timestamp of the time 1 month ago from now?

I know I need to use Date()

What do you mean "one month ago"? The time equivalent to 30 days ago? The same day in the previous month? If the latter, how to handle the 31st day when the previous month has < 31 days? Once you figure out what you want, it should be easy enough to get it working. — Fabrício Matté, Jun 04 '14 at 23:19
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date — japrescott, Jun 04 '14 at 23:20

RobG · Accepted Answer · 2021-01-28T23:35:08.477

71

A simplistic answer is:

// Get a date object for the current time
var d = new Date();

// Set it to one month ago
d.setMonth(d.getMonth() - 1);

// Zero the time component
d.setHours(0, 0, 0, 0);

// Get the time value in milliseconds and convert to seconds
console.log(d/1000|0);

Note that if you subtract one month from 31 July you get 31 June, which will be converted to 1 July. similarly, 31 March will go to 31 February which will convert to 2 or 3 March depending on whether it's in a leap year or not.

So you need to check the month:

var d = new Date();
var m = d.getMonth();
d.setMonth(d.getMonth() - 1);

// If still in same month, set date to last day of 
// previous month
if (d.getMonth() == m) d.setDate(0);
d.setHours(0, 0, 0, 0);

// Get the time value in milliseconds and convert to seconds
console.log(d / 1000 | 0);

Note that JavaScript time values are in milliseconds since 1970-01-01T00:00:00Z, whereas UNIX time values are in seconds since the same epoch, hence the division by 1000.

edited Jan 28 '21 at 23:35

answered Jun 04 '14 at 23:34

RobG

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For anyone wondering, yes, you can do a d.setMonth for a negative value (in the case of January). I was pleasantly surprised that worked and this code sample still works in that case. – ryanm Dec 07 '15 at 19:50
How to get month as 12 in case of January. I am getting month as 11 – Nehal Jaisalmeria Jan 28 '21 at 11:21
1

@NehalJaisalmeria—I don't understand your issue. For January, *getMonth* returns 0. Subtracting 1 gives -1, *setMonth* converts that to December the previous year, which is ECMAScript month 11. See [*getMonth in javascript gives previous month*](https://stackoverflow.com/questions/18624326/getmonth-in-javascript-gives-previous-month). – RobG Jan 28 '21 at 23:44
On the 31st of May 2023 (today), I run d.setMonth(d.getMonth() - 1); and get May 1st 2023 ? – Fiach Reid May 31 '23 at 11:28
@FiachReid—yes, because 31 May less one month goes to 31 April, which doesn't exist, so it rolls over to 1 May. See [*JavaScript function to add X months to a date*](https://stackoverflow.com/questions/2706125/javascript-function-to-add-x-months-to-a-date). – RobG Jun 08 '23 at 12:17

Mr.Cocococo · Answer 2 · 2014-06-04T23:42:13.857

24

var d = new Date();

And set the month to a month before. (EDITED)

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

edited Jun 04 '14 at 23:42

answered Jun 04 '14 at 23:29

Mr.Cocococo

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You are right. my bad. – Mr.Cocococo Jun 04 '14 at 23:41
what happens if you do this in January? Will it go to previous year? – hansmbakker Oct 03 '22 at 19:22
yes, it will go to previous year – Mr.Cocococo Oct 06 '22 at 04:43

score 20 · Answer 3 · answered Jun 04 '14 at 23:22

20

You could take a look at Moment.JS. It has a bunch of useful date related methods.

You could do:

moment().subtract('months', 1).unix()

answered Jun 04 '14 at 23:22

NRaf

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Javascript get timestamp of 1 month ago

3 Answers3