Discrepancy in JSON.stringify of date values in different browsers

Question

I have this code in an HTML page:

alert(JSON.stringify(new Date()));

I'm including the latest json2.js (2009-09-29 version) in my page to support older browsers without JSON.stringify(). I also have jquery-1.3.2.js included. I believe in newer browsers with native JSON support, it just passes through to the native JSON feature.

Here's the results I get in different browsers:

IE 8 on Windows XP: "2010-02-07T21:39:32Z"
Chrome 4.0 on Windows XP: "2010-02-07T21:39:59Z"
Firefox 3.0 of Windows XP: "2010-02-07T21:40:41Z"
Chrome 4.0 on Ubuntu linux:  "2010-02-07T21:41:49Z"
Firefox 3.0 on Ubuntu linux:  "2010-02-07T21:42:44Z"
Chrome 4.0 on Mac OSX: "2010-02-07T21:43:56Z"
Safari on Mac OSX: "2010-02-07T21:45:21Z"
Firefox 3.5 on Mac OSX: "2010-02-07T21:44:10.101Z"

Notice the last one? It contains milliseconds, and none of the others do. I don't have FF3.5 installed on any other systems, but I'm assuming they would have the same results.

Is there something I can do to make all dates on all platforms stringify the same? My backend REST service can be configured with a format string to deserialize JSON dates, but it can't support multiple formats, just one.

Answer 1

I got this working adding the following javascript:

// Added to make dates format to ISO8601
Date.prototype.toJSON = function (key) {
    function f(n) {
        // Format integers to have at least two digits.
        return n < 10 ? '0' + n : n;
    }

    return this.getUTCFullYear()   + '-' +
         f(this.getUTCMonth() + 1) + '-' +
         f(this.getUTCDate())      + 'T' +
         f(this.getUTCHours())     + ':' +
         f(this.getUTCMinutes())   + ':' +
         f(this.getUTCSeconds())   + '.' +
         f(this.getUTCMilliseconds())   + 'Z';
};

I'm sure this probably slows down the serialization, but it seems to make things consistent across browsers.