Javascript get date 30 days ago

Question

I am trying to populate two date input fields, one with today's date and one with the date 30 days ago(last month).

I am getting an error in my console: priordate.getDate is not a function

Here is my code, not sure what I am doing wrong:

//today's date

var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1;//January is 0, so always add + 1
var yyyy = today.getFullYear();
if(dd<10){dd='0'+dd};
if(mm<10){mm='0'+mm};
today = yyyy+'-'+mm+'-'+dd;

//30 days ago

var beforedate = new Date();
var priordate = new Date().setDate(beforedate.getDate()-30);
var dd2 = priordate.getDate();
var mm2 = priordate.getMonth()+1;//January is 0, so always add + 1
var yyyy2 = priordate.getFullYear();
if(dd2<10){dd2='0'+dd2};
if(mm2<10){mm2='0'+mm2};
var datefrommonthago = yyyy2+'-'+mm2+'-'+dd2;

// Set inputs with the date variables:

$("#fromdate").val(datefrommonthago);
$("#todate").val(today);

Did you try using [`moment.js`](http://momentjs.com/) or is that not an option? — ssc-hrep3, May 23 '17 at 10:59
I am using phonegap with the intention of making this an app, so if possible I would like to avoid external libraries. — Bruno, May 23 '17 at 11:00
The return value of `setDate()` is not a Date, so you need to split this line: `var priordate = new Date().setDate(beforedate.getDate()-30);` — ssc-hrep3, May 23 '17 at 11:03

Nick is tired · Accepted Answer · 2017-05-23T11:10:42.987

6

You'll instead want to use:

var priordate = new Date(new Date().setDate(beforedate.getDate()-30));

if you want it on one line. By using:

new Date().setDate(beforedate.getDate()-30);

you're returning the time since epoch (a number, not a date) and assigning it to priordate, but it's not a Date anymore and so does not have the getDate function.

edited May 23 '17 at 11:10

answered May 23 '17 at 11:01

Nick is tired

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score 3 · Answer 2 · answered May 23 '17 at 11:02

3

This is because setDate() returns a number, not a Date Object.

In any I case I'd strongly recommend using momentjs or date-fns as the internal Date object in JavaScript is broken in all kind of ways. See this talk: https://www.youtube.com/watch?v=aVuor-VAWTI

answered May 23 '17 at 11:02

marvinhagemeister

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I was under the impression that only using javascript was possible when developing with cordova/phonegap. I'll definitely check that video and might consider using moment.js. Thanks for your input! – Bruno May 23 '17 at 11:06

score 1 · Answer 3 · answered May 23 '17 at 11:02

1

Change this:

var priordate = new Date().setDate(beforedate.getDate()-30);

to this:

var priordate = new Date();
priordate.setDate(beforedate.getDate()-30);

answered May 23 '17 at 11:02

rafaelcastrocouto

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Aha! I see where I went wrong. Thank you so much, I understand better now :) – Bruno May 23 '17 at 11:04

Javascript get date 30 days ago

3 Answers3