Convert specific date in Javascript

Question

I have problem with convert date which I get from API. Format is for example "16/09/25" I try do it like this var x = new Date(dateFromApi) and console thorw me error.

Answer 1

Parsing a date string is very simple. A function that will work in any host from IE 4 onward is:

function parseDMY(s) {
  var b = s.split(/\D/);
  return new Date(b[2], b[1]-1, b[0]);
}

console.log(parseDMY('16/09/25'));

Where the year is >= 0 or <= 99, 1900 is added so 25 becomes 1925. Preserving years in this range (so 25 is 0025) requires an additional line of code.

Answer 2

Your format is DD/MM/YY and it is not accepted by Date and will throw an error.

This is because, as mentioned by @MattJohnson, the accepted Date formats vary by locale and the only official format is YYYY-MM-DD (which is derived from ISO date string. Read here).

In most cases, Date will accept the format YY-MM-DD. So we can simply do this:

var date = "16/09/25"; // date received from API

var split_date = date.split('/'); // outputs ["16","09",""25"]

var rearranged_date = [split_date[1], split_date[0], split_date[2]].join('/'); // outputs "09/16/25"

var proper_date = new Date(rearranged_date);

In other cases, it is best to provide the full-year YYYY instead of just YY.

Answer 3

It is safest to provide the Date constructor with the individual parts of the date (i.e., year, month and day of the month).

In ES6 you can provide those elements like this:

var x = new Date(...dateFromApi.split('/').reverse().map( (p,i) => p-(i%2) ));

The map is needed to subtract one from the month number, as it should be zero-based in numeric format.

Note the new Date(year, month, day) version of the constructor will assume 19xx when you provide only 2 digits.

var dateFromApi = "16/09/25"
var x = new Date(...dateFromApi.split('/').reverse().map( (p,i) => p-(i%2) ));
console.log(x.toDateString());

In ES5, it would be a bit longer, like this:

new (Date.bind.apply(Date, (dateFromApi+'/').split('/').reverse()
    .map(function (p,i) { return p-(i==2); })));

var dateFromApi = "16/09/25"
var x = new (Date.bind.apply(Date, (dateFromApi+'/').split('/').reverse()
            .map(function (p,i) { return p-(i==2); })));
console.log(x.toDateString());

Of course, this assumes that the input format is consistently in the order DD/MM/YY (or D/MM/YYYY, as long as the order is the same); that valid dates are passed, and that you accept how 2-digit years are mapped to 4-digit years.