Date vs new Date in JavaScript

new Date() takes an ordinal and returns a Date object.
What does Date() do, and how come it gives a different time?

>>> new Date(1329429600000)
Date {Fri Feb 17 2012 00:00:00 GMT+0200 (القدس Standard Time)}
>>> Date(1329429600000)
"Tue Mar 06 2012 15:29:58 GMT+0200 (Jerusalem Standard Time)"

From the specs:

When Date is called as a function rather than as a constructor, it returns a String representing the current time (UTC).

and:

When Date is called as part of a new expression, it is a constructor: it initialises the newly created object.

So, new Date(...) returns an object such that obj instanceof Date is true, whereas Date(...) basically returns the same as new Date().toString().

new Date creates a new Date object that you can modify or initialize with a different date while Date returns a string of the current date/time, ignoring its arguments.

Check out JavaScript Date for a quick API reference and code test bed. You can see the Date() function called without new does not take any parameters and always returns a string representation of the current date/time. If you modify the sample to be:

console.log(Date());
console.log(Date(1329429600000));

You'll find the results for both are the same (because JavaScript ignores extra arguments passed to functions):

Wed Apr 11 2012 09:58:11 GMT-0700 (PDT)
Wed Apr 11 2012 09:58:11 GMT-0700 (PDT)