16

I receive date/time objects from user input, and would like to parse them to a javascript Date object. The date is in the format: 02/06/2018 00:59:03 which means second of june, 2018; UK locale. Although this seems extremely trivial and a super wide use case scenario, I can't seem to find anything in the documentation how to specify the locale I wish to use for parsing.

What the parser does is simply assume I am using US locale format, which defaults to having first the month, then the day, and then the year, so it mixes up month and day.

Currently the only available option I see is writing my own parser, which is fine ish (it is not, of course, as I might tomorrow need another locale), but seems a little 1980ies to me.

Maybe I overlooked something in the documentation. But does anyone have any other solution? Would be greatly appreciated.

P.s. I can hardly imagine this has not been asked yet, but my search did not turn up much either.

Frido Emans
  • 5,120
  • 2
  • 27
  • 42

1 Answers1

10

From MDN's Date() documentation:

Note: parsing of date strings with the Date constructor (and Date.parse, they are equivalent) is strongly discouraged due to browser differences and inconsistencies. Support for RFC 2822 format strings is by convention only. Support for ISO 8601 formats differs in that date-only strings (e.g. "1970-01-01") are treated as UTC, not local.

If your input is structured and the format is constant, writing your own parser should be straightforward. Here's an approach using a regular expression.

var dateString = '02/06/2018 00:59:03';

var dateParser = /(\d{2})\/(\d{2})\/(\d{4}) (\d{2}):(\d{2}):(\d{2})/;
var match = dateString.match(dateParser);
var date = new Date(
    match[3],  // year
    match[2]-1,  // monthIndex
    match[1],  // day
    match[4],  // hours
    match[5],  // minutes
    match[6]  //seconds
);

console.log('Input: ' + dateString);
console.log('Output (en-US): ' + date.toLocaleString('en-US'));
console.log('Output (en-GB): ' + date.toLocaleString('en-GB'));

Alternatively, string splitting would be pretty easy as well (i.e. split by a space, then split the first result by / and the second result by :).

TylerH
  • 20,799
  • 66
  • 75
  • 101
chuckx
  • 6,484
  • 1
  • 22
  • 23
  • 5
    Thanks @chuckx for the accurate answer (although not what I hoped); plus the parser included. I would think that these days, with javascript so advanced, one would expect to have reverse functions for things like toLocaleString() as well. – Frido Emans Jun 10 '18 at 08:57
  • My answer applies when you're sticking to vanilla JS. However, as @Andreas mentioned, momentjs is a library which addresses your concern. Specifically, see [the parsing functionality where you can specify the input format](http://momentjs.com/docs/#/parsing/string-format/). – chuckx Jun 10 '18 at 09:00
  • Yes, I failed to mention that I was looking for a vanilla solution, otherwise I would jump immediately to using a library. – Frido Emans Jun 10 '18 at 09:08
  • xor: this might help https://stackoverflow.com/a/53211160/529663. It returns the formatting string for dates in a locale. – lenooh Apr 19 '21 at 10:50
  • And in typescript, you need to use this syntax to avoid errors: `parseInt(match![3]), // year` etc. – Matthieu Charbonnier May 17 '22 at 07:54