Date javascript

Question

Hi,

I am trying to understand more about the Date object in javascript. I thought that when you call valueOf(), you get the amount of milliseconds since january 1, 1970. So what I would expect is that the following should return exactly zero;

alert((new Date(1970, 1, 1).valueOf() )/ ( 86400 * 1000));

but it does not, it returns 30.958333333333332. What am I missing?

gr,

Coen

Answer 1

The method you are searching is .getTime() not .valueOf()

Answer 2

new Date(1970, 1, 1) actually is Feb. Months are zero-indexed. Try changing it to new Date(1970, 0, 1).

Answer 3

Months are zero based in Date objects.

Answer 4

January 1st, 1970 is new Date(1970, 0, 1), since months start at 0 = January.

Answer 5

The first of january 1970 with the Date object is new Date(1970, 0, 1)

Answer 6

If you're looking to work with the unix epoch time, you have a few options

• UTC() Returns the number of milliseconds in a date string since midnight of January 1, 1970, according to universal time
• setTime() Sets a date and time by adding or subtracting a specified number of milliseconds to/from midnight January 1, 1970
• parse() Parses a date string and returns the number of milliseconds since midnight of January 1, 1970
• getTime() Returns the number of milliseconds since midnight Jan 1, 1970

valueOf() returns a primitive of the value, I'd stay away from it and work with the above options.

source: http://www.w3schools.com/jsref/jsref_obj_date.asp.

edit: also, your asking for Feb 1, 1970

use this, it's dangerous to go alone:

var d=new Date(1970, 0, 1);
document.write(d.getTime());

or

var d= Date.parse("Jan 1, 1970"); //Note, we don't use NEW keyword.
document.write(d);

Remember, epcoh is Wed Dec 31 1969 19:00:00 GMT-0500. If you use .getTime() you'll see UTC time Thu, 01 Jan 1970 00:00:00 GMT +0000.

Answer 7

Second parameter, month, starts with 0, so you need to do:

alert((new Date(1970, 0, 1).valueOf() )/ ( 86400 * 1000));

but even with this you'll get the offset, in seconds, off GMT.

the value you posted says you are GMT +1 : )

Answer 8

it was the month that should have been 0 in combination with an hour difference from GMT

alert((new Date(1970, 0, 1, 1, 0, 0, 0).valueOf()));

produces 0