Question

Google calendar throws at me rfc3339, but all my dates are in those milliseconds since jan 1970.

rfc3999:

2012-07-04T18:10:00.000+09:00

javascript current time: (new Date()).getTime():

1341346502585

I prefer the the milliseconds because I only deal in countdowns and not in dates.

Answer 1

Datetimes in that format, with 3 decimal places and a “T”, have well-defined behaviour when passed to Date.parse or the Date constructor:

console.log(Date.parse('2012-07-04T18:10:00.000+09:00'));
// 1341393000000 on all conforming engines

You have to be careful to always provide inputs that conform to the JavaScript specification, though, or you might unknowingly be falling back on implementation-defined parsing, which, being implementation-defined, isn’t reliable across browsers and environments. For those other formats, there are options like manual parsing with regular expressions:

var googleDate = /^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})\.(\d{3})([+-]\d{2}):(\d{2})$/;

function parseGoogleDate(d) {
    var m = googleDate.exec(d);
    var year   = +m[1];
    var month  = +m[2];
    var day    = +m[3];
    var hour   = +m[4];
    var minute = +m[5];
    var second = +m[6];
    var msec   = +m[7];
    var tzHour = +m[8];
    var tzMin  = +m[9];
    var tzOffset = tzHour * 60 + tzMin;

    return Date.UTC(year, month - 1, day, hour, minute - tzOffset, second, msec);
}

console.log(parseGoogleDate('2012-07-04T18:10:00.000+09:00'));

or full-featured libraries like Moment.js.