EcmaScript 5's Date Extensions

Okay, so you want to utilize some of the niceties of the new EcmaScript 5 extensions to Date.  Namely they've added a nice instantiation from an ISO-8601-style string, as well as a Date.prototype.toISOString method definition.  In addition there are Date.UTC and Date.now methods defined.  As the nice guys over at Mozilla have offered script based extensions to Arrays to support their method extensions there, I wanted to do something similar for Date instances.  I've managed to do this, and have had it done since the ES5 specs were released, but figured I should put this out there for anyone interested.

var epoch1 = new Date("1970-01-01T00:00:00.000Z");
var epoch2 = new Date(0);

if (epoch1.getTime() == epoch2.getTime())
    alert("Epochs match!");
    
alert(epoch1.toString()); //localized date instance of the JS epoch
alert(epoch2.toISOString()); // "1970-01-01T00:00:00.000Z"
alert(epoch1 instanceof Date); // true
alert(epoch1.constructor == Date); //true
alert(Date.UTC(1970,0,1,0,0,0,0)); // 0

I also have a few convenience methods for handling Microsoft's JSON encoded strings. As well as rolling a date from a "Local" or "UTC" version.

DateExtensions.js (11.67 kb)

Edit 2010-01-08: I added missing support for .constructor == Date