how can I compare dates in array to find the earliest one?

Question

I have a variable called dateArray with dates in it for example

["09/09/2009", "16/07/2010", "29/01/2001"]

and I want to find the earliest one with a for loop so the result will be

"29/01/2001" - or dateArray[2]

the language is javascript

http://stackoverflow.com/questions/492994/compare-two-dates-with-javascript — Prasad, Jul 27 '15 at 12:00
Reverse the strings, to a string sorting, take the first (or last) element. — Sirko, Jul 27 '15 at 12:01

score 1 · Accepted Answer · answered Jul 27 '15 at 12:03

1

Sometimes the most basic approach is the best:

var dates = ["09/09/2009", "16/07/2010", "29/01/2001"];
var min = dates[0];
for(var i = 1; i < dates.length; i++) {
  if (fDate(dates[i]) < fDate(min))
    min = dates[i];
}

alert(min);

// create a proper Date object from the string
function fDate(s) {
  var d = new Date();
  s = s.split('/');
  d.setFullYear(s[2]);
  d.setMonth(s[1]);
  d.setDate(s[0]);
  return d;
}

The code I wrote for you above converts each string into a Date object, and then finds the minimum (the earliest date) from them. No string hacks, just straightforward date comparison. It returns the original string from the array.

answered Jul 27 '15 at 12:03

Shomz

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It'd be faster to use `new Date('dd/mm/yyyy')` to create the Date objects (assuming you're running the JS in a locality that uses that format). – Blazemonger Jul 27 '15 at 13:38
Yes, a few nanoseconds. However, that format won't work with the Date object (but `mm/dd/yyyy` will) and you'd lose performance on string manipulation. Just saw your edit about locality - yeah, that would probably cause a lot of errors/wrong dates with different users, I'd rather not do it. – Shomz Jul 27 '15 at 13:41
Sorry, no. JavaScript will recognize whether the local user uses `mm/dd/yyyy` or `dd/mm/yyyy` formats and process the string accordingly. The only good reason to do it your way is if an international audience is expected. – Blazemonger Jul 27 '15 at 13:43
Hmmm, `new Date("29/01/2001")` fails for me, I don't think it can recognize the format automatically. Are you sure about that? Are both `new Date("29/01/2001")` and `new Date("01/29/2001")` working for you? – Shomz Jul 27 '15 at 13:43
How are your computer system preferences set up? Are you using a localized browser or an American one? My brief research on Wikipedia suggests that `29.01.2001` is your preferred local format anyway. – Blazemonger Jul 27 '15 at 13:46
It should be an American one. Yes, `29.01.2001.` seems natural to me, but not to the Date function. – Shomz Jul 27 '15 at 13:47
At least when you're parsing on an American system, this is wrong. Month is zero-based. I had to do d.setMonth(s[1] - 1); get get it to work. – Jamie Mar 31 '18 at 00:01
Also, I found this to be more concise: d.setFullYear(s[2], s[0] - 1, s[1]); – Jamie Mar 31 '18 at 00:30

score 1 · Answer 2 · answered Jul 27 '15 at 13:33

   var dateArray = ["09/09/1980","09/09/2009", "16/07/2010", "29/01/1990"];
   var first = dateArray[0].split("/").reverse().join("-");
   var arrayLength = dateArray.length;
   for(var i=1; i< arrayLength; i++){
   second = dateArray[i].split("/").reverse().join("-");
     if (first > second){
        first = second;
     }
   }
alert(first);

hsz · Answer 3 · 2015-07-27T12:12:42.023

0

You can try with momentjs library:

var dateArray = ["09/09/2009", "16/07/2010", "29/01/2001"],
    format = 'DD/MM/YYYY',
    minDate = moment(dateArray[0], format),
    minDateKey = 0;

for (var i = 1; i < dateArray.length; i++) {
  var date = moment(dateArray[i], format);
  if (minDate > date) {
    minDate = date;
    minDateKey = i;
  }
}

alert(minDateKey);

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.10.3/moment.min.js"></script>

edited Jul 27 '15 at 12:12

answered Jul 27 '15 at 12:10

hsz

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Why would you load a library for something so simple? It reminds me of one of those "use jQuery for everything" topics... – Shomz Jul 27 '15 at 12:12
@Shomz Sure, but working with JS `Date` object is always a painful. – hsz Jul 27 '15 at 12:13
That's true, though it's just a couple of lines in this case. – Shomz Jul 27 '15 at 12:14

score -1 · Answer 4 · edited May 23 '17 at 12:06

-1

The easiest way is to create dates object and the you can check grater/equal.. (date1 > date2)

Example to create date: Convert dd-mm-yyyy string to date

edited May 23 '17 at 12:06

Community

1
1

answered Jul 27 '15 at 12:01

Roy Shmuli

4,979
1
24
38

user3270602 · Answer 5 · 2015-07-27T12:51:52.503

-2

You can get the earliest date by the below loop

var dateArray = ["09/09/2009", "16/07/2010", "29/01/2001"];
    alert(dateArray)//convert string to date object
var earliest = dateArray[0];
for(i=0; i<=dateArray.length; i++){
  var date1 = dateArray[i];
  if (date1 > earliest) {
     earliest = date1;

  }
}
alert(earliest)

edited Jul 27 '15 at 12:51

answered Jul 27 '15 at 12:01

user3270602

696
7
15

This is the worst solution provided, will not work at all as you are just doing string comparisons, please do NOT post incorrect code as solution – Sayantan May 29 '18 at 02:59

how can I compare dates in array to find the earliest one?

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