javascript setUTCMilliseconds is wrong? Otherwise, I'm wrong

Question

Am I implementing setUTCMilliseconds incorrectly? I get the incorrect date for any value I put in. Here is just one example of a wrong value. All my test data resolves to May 24 (the future from now) in JS, but in C# or using quick online conversion tools, my UTS MS are correct.

any thoughts?

function parseDate(epoch) {   
    var d = new Date();

    //tried this too, but it shows me the actual epoch 1970 date instead
    //var d = new Date(0);

    //EDIT: this should be seconds in combination with Date(0)
    d.setUTCMilliseconds(parseInt(epoch)); 

    return d.toString();
}

 // 1336423503 -> Should be Mon May 07 2012 13:45:03 GMT-7

 // javascript says
 Thu May 24 2012 05:03:21 GMT-0700 (Pacific Daylight Time) 

Answer 1

From a similar question:

var utcMilliseconds = 1234567890000;
var d = new Date(0); // The 0 there is the key, which sets the date to the epoch
d.setUTCMilliseconds(utcMilliseconds);

See Convert UTC Epoch to local date with javascript.

Answer 2

To convert a UTC time in seconds to a local date object:

function makeUTC(secs) {
  return new Date(Date.UTC(1970,0,1,0,0, secs, 0));
}

Note that the epoch is 1970-01-01T00:00:00.0Z

Answer 3

Just use the Date() constructor with milliseconds as a number:

> new Date(1336423503 * 1000)
2012-05-07T20:45:03.000

There is no need to create a Date object and setUTCMilliseconds afterwards.