I want to detect with JavaScript or jQuery what are the Regional Settings of the current user in NewForm.
This is want I want to get from user:

try this one:
var url = ctx.HttpRoot+"/_layouts/regionalsetng.aspx?Type=User";
$.get(url,function(data){
$(data).find("select[name=ctl00$PlaceHolderMain$ctl00$ctl00$DdlwebLCID]").find(":selected").each(function(){
var lcid = $(this).attr("value");
var cultureInfo = $(this).text();
});
});