javascript - How To Change ISO Date String to Date Object?

Question

I am stuck in a weird situation and unfortunately, even after doing some RnD and googling, I am unable to solve this problem.

I have a date string in ISO format, like 2014-11-03T19:38:34.203Z and i want to convert it into a date object with new Date() method.

But when i do so, output is:

var isoDate = '2014-11-03T19:38:34.203Z';
console.log(new Date(isoDate)); //output is: Tue Nov 04 2014 01:08:34 GMT+0530 (IST)

The date which i passed is of 3 Nov,2014 and the output is 4 Nov,2014 and it's because of GMT +5.30 of our local time(IST).

So, is there any generic method with which i can get the date object which return the date of Nov 3,2014.

NOTE: I don't have any issues with timestamp. We can change time string to zero with setHours() method. The only thing which i want is date object like new Date() having date of 3 Nov,2014.

Answer 1

Do not pass strings to the Date constructor, it is notoriously bad at parsing strings. IE 8, for one, will not parse ISO 8601 format strings at all and return NaN. It's really simple to write your own parser:

function parseISOString(s) {
  var b = s.split(/D+/);
  return new Date(Date.UTC(b[0], --b[1], b[2], b[3], b[4], b[5], b[6]));
}

Note also that if the time is 19:38:34.203 UTC and your timezone is UTC +0530, then the time in that timezone is 01:08:34 am on the following day, hence the difference in dates. For example, for a person on the east coast of Australia but not observing daylight saving (i.e. UTC +10), it's equivalent to:

4 November, 2014 05:38:34

Edit

So if you want to return it to an ISO date, you can use the getISO* methods to create whatever format that suits, e.g.

function isoFormatDMY(d) {  
  function pad(n) {return (n<10? '0' :  '') + n}
  return pad(d.getUTCDate()) + '/' + pad(d.getUTCMonth() + 1) + '/' + d.getUTCFullYear();
}

var s = '2014-11-03T19:38:34.203Z';
var date = parseISOString(s);

console.log(isoFormatDMY(date)) // 03/11/2014

or use ES5's toISOString:

 parseISOString('2014-11-03T19:38:34.203Z').toISOString(); // 2014-11-03T19:38:34.203Z

A simple polyfill for pre ES5 browsers:

if (!Date.prototype.toISOString) {

  Date.prototype.toISOString = function() {

    var d = this;

    // Padding functions 
    function pad(n) {return (n<10? '0' :  '') + n}
    function padd(n){return (n<100? '0' : '') + pad(n)}

    return d.getUTCFullYear() + '-' + pad(d.getUTCMonth() + 1) + '-' + pad(d.getUTCDate()) +
           'T' + pad(d.getUTCHours()) + ':' + pad(d.getUTCMinutes()) + ':' + 
           pad(d.getUTCSeconds()) + '.' + padd(d.getMilliseconds()) + 'Z';
  }
}