how to get next validate day? Adding number of days is not working

Question

I have the following script to check if a date is valid:

var text = '2/31/2013'; 
var comp = text.split('/'); 
var m = parseInt(comp[0], 10); 
var d = parseInt(comp[1], 10); 
var y = parseInt(comp[2], 10); 
var date = new Date(y,m-1,d); 
if(date.getFullYear() == y && date.getMonth() + 1 == m && date.getDate() == d) {
    console.log('Valid date'); 
}
else {
    console.log('Invalid date');
    var NextValidDate = new Date(y,m-1,d+1);
    console.log(NextValidDate);    
}

I would like to jump now to the next correct date. In the sample case is this the 01. March 2012.

But how to get it? NextValidDate gives not always a correct date.

I do not wont to add a number of days. Here I do not know them. The days to add are different on februar the 29, 30 ,31. And it is not possible to add days on unvalid dates. — hamburger, Jun 21 '13 at 20:31
Voted to reopen because it is, after all, not a duplicate. Though I think the question could be phrased better, i.e. provide an explanation of the context. — Felix Kling, Jun 22 '13 at 11:29

score 1 · Answer 1 · answered Jun 21 '13 at 20:28

1

var originalDate = new Date(2013, 2, 31);
var nextDate = new Date(originalDate.getFullYear(), originalDate.getMonth(), originalDate.getDay() + 1);

answered Jun 21 '13 at 20:28

LaurentG

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in my http://jsfiddle.net/UeQAK/89/ it gives the 3the of march. But correct is the 1th. – hamburger Jun 21 '13 at 20:37
1

@hamburger: Is it? `02/31/2013` is three days after `02/28/2013`, which is `03/03/2013`. – Felix Kling Jun 21 '13 at 20:39
@FelixKling: I do not understand. It doesn't matter you have the 29/30/31. the result should always be the 01.03.2012 – hamburger Jun 21 '13 at 20:42

Felix Kling · Accepted Answer · 2013-06-21T20:53:10.737

1

According to your logic, if a date does not exist (which can only happen if the month has less days than provided as input), then the first day of the next month is the next "correct" date.

In that case you create the next valid date by adding one to the month and set the days to 1:

var NextValidDate = new Date(y, (m-1) + 1, 1);

edited Jun 21 '13 at 20:53

answered Jun 21 '13 at 20:41

Felix Kling

795,719
175
1,089
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Thats logic. Thanks I didn't got that logic. – hamburger Jun 21 '13 at 21:04
This logic works only if you move forward. What if you go backwards? – hamburger Jun 21 '13 at 21:18
When would you want to go backwards? You mean getting the last date of the months instead of the first of the next month? See http://stackoverflow.com/q/222309/218196. Basically you do `new Date(y, (m-1) + 1, 0);` i.e. use `0` instead of `1`. – Felix Kling Jun 21 '13 at 21:24
I have three select-boxes (year, month, day). If I change the month the days shout be adapted. – hamburger Jun 22 '13 at 09:18
That makes sense. As I said, just use `0` instead of `1` for the day. – Felix Kling Jun 22 '13 at 09:20

score 0 · Answer 3 · answered Jun 21 '13 at 20:48

Part of the problem is that most browsers will interpret new Date(2013, 1, 31) as March 4, 2013 (or 2/28/2013 + 3 days). Thus, while:

date.getFullYear() == y && date.getMonth() + 1 == m && date.getDate() == d

returns false, the parsed date is still a technically valid date. I suspect you simply want to advance to the next month in the event that m/d/y entered is not the same m/d/y that is parsed. If that's the case, make your nextValidDate the first of the following month:

var text = '2/31/2013',
    comp = text.split('/'),
    m = parseInt(comp[0], 10),
    d = parseInt(comp[1], 10),
    y = parseInt(comp[2], 10),
    date = new Date(y, m - 1, d),
    nextValidDate;
if (date.getFullYear() === y && date.getMonth() + 1 === m && date.getDate() === d) {
    console.log('Valid date'); 
} else {
    console.log('Invalid date');
    nextValidDate = new Date(y, m, 1);
    console.log('Next valid date: ' + nextValidDate);
}

What can I do if I come backwards from the first of march to februar or from 1. december to 30. november? Do I have to ckeck it for each month separately? — hamburger, Jun 21 '13 at 21:20

how to get next validate day? Adding number of days is not working

3 Answers3