javascript date with string

Question

I'm trying to convert a date in javascript from MM/dd/yyyy to yyyy/MM/dd

so this works:

var d = new Date("08/08/2012");
dateString = d.getFullYear() + "/" + d.getMonth() + "/" + d.getDate();
document.write(dateString);

output = 2012年7月8日

///////////////////////////////////////////////////

this does not:

var dateString = "08/08/2012";
var d = new Date(dateString);
dateString = d.getFullYear() + "/" + d.getMonth() + "/" + d.getDate();
document.write(dateString);

and neither does this:

var dateString = "08/08/2012";
var d = Date.parse(dateString);
dateString = d.getFullYear() + "/" + d.getMonth() + "/" + d.getDate();
document.write(dateString);

how do I make it work with a string variable? thanks

~Myy

• Jordan: What does the browser's console log when it tries to execute the code that doesn't work?
• Marcelo Cantos: Are you saying that you want 08/08/2012 to print as 2012年7月8日 (i.e., with the month changed from 08 to 7)?
• Myy: no, I was having a problem using a string variable vs the new Date() function.

Answer 1

var dateString = "08/08/2012";
var d = new Date(dateString);
dateString = d.getFullYear() + "/" + d.getMonth() + "/" + d.getDate();
document.write(dateString);

That should, and does, work. Keep in mind that JavaScript stores months as a zero-indexed value.

If you want to have leading zeros, then you'll have to do some magic:

var dateString = "08/08/2012";
var d = new Date(dateString);
dateString = d.getFullYear() + "/" + ('0' + (d.getMonth()+1)).slice(-2) + "/" + ('0' + d.getDate()).slice(-2);
document.write(dateString);​

jsFiddle

The reason why your Date.parse( ) example is not working, is because that function returns a timestamp (number of milliseconds since 1970), instead of a Date object. Therefore, you can't call functions like getFullYear() on the timestamp.

• The Muffin Man: The million dollar question is why Date.parse doesn't work.
• jeffjenx: @Nick Date.parse does work, but it doesn't return a Date object. It returns a timestamp.
• Myy: I swear I tried the second method time after time, and it didn't work, and now that I tried again it worked. I guess I was missing something, Thanks for the quick response!
• The Muffin Man: @MrSlayer I really wish they would have named the function better.

Answer 2

If all you need to do is re-order the values, you can do:

var dateString = "08/08/2012";
var dateElements = dateString.split("/");
var outputDateString = dateElements[2] + "/" + dateElements[0] + "/" + dateElements[1];
document.write(outputDateString );

Answer 3

I can confirm with MrSlayer that the code works in jsFiddle.

Your attempts at using Date.parse() should actuall be using Date(String(dateString)).

Don't forget to add 1 for each month.