How to detect date format defined by browser?

Question

I'm using HTML5 input type=date field and because some browsers still don't support this feature, I would like to create error validation message for browsers that display just normal text field instead of date field. This error message should look like

Please enter date in format: ...

But I need to find the correct format, that the browser is set to. Is there any php/js/jQuery way how to find out this?

Answer 1

Thanks to @Jose Vega's answer I was able to find very easy way how to do it.

     var now=new Date(2013,11,31);
     var str=now.toLocaleDateString();
     str=str.replace("31","dd");
     str=str.replace("12","mm");
     str=str.replace("2013","yyyy");

Error message:

"Please enter date in format:" + str