Converting a string to a date in JavaScript

The best string format for string parsing is the date ISO format together with the JavaScript Date object constructor.

Examples of ISO format: YYYY-MM-DD or YYYY-MM-DDTHH:MM:SS.

But wait! Just using the "ISO format" doesn't work reliably by itself. String are sometimes parsed as UTC and sometimes as localtime (based on browser vendor and version). The best practice should always be to store dates as UTC and make computations as UTC.

To parse a date as UTC, append a Z - e.g.: new Date('2011-04-11T10:20:30Z').

To display a date in UTC, use .toUTCString(),
to display a date in user's local time, use .toString().

More info on MDN | Date and this answer.

For old Internet Explorer compatibility (IE versions less than 9 do not support ISO format in Date constructor), you should split datetime string representation to it's parts and then you can use constructor using datetime parts, e.g.: new Date('2011', '04' - 1, '11', '11', '51', '00'). Note that the number of the month must be 1 less.

Alternate method - use an appropriate library:

You can also take advantage of the library Moment.js that allows parsing date with the specified time zone.

Unfortunately I found out that

var mydate = new Date('2014-04-03');
console.log(mydate.toDateString());

returns "Wed Apr 02 2014". I know it sounds crazy, but it happens for some users.

The bulletproof solution is the following:

var parts ='2014-04-03'.split('-');
// Please pay attention to the month (parts[1]); JavaScript counts months from 0:
// January - 0, February - 1, etc.
var mydate = new Date(parts[0], parts[1] - 1, parts[2]); 
console.log(mydate.toDateString());

var st = "26.04.2013";
var pattern = /(\d{2})\.(\d{2})\.(\d{4})/;
var dt = new Date(st.replace(pattern,'$3-$2-$1'));

And the output will be:

dt => Date {Fri Apr 26 2013}