Answer and Explanation:
Using javascript:
function dayof_theweek(){
var TodayDate = window. prompt("enter today's date in the format 'year, month, day' ");
var Datenow=new date(TodayDate);
var Dayofweek=Datenow.getday();
var Days=["monday","Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"];
if(Dayofweek==indexOf(Days[Dayofweek]))
{
document.createTextnode(Days[Dayofweek]);
}
}
The program above uses a date object which uses the method getday to get the day of the week(get day returns an integer from 0 to 6).we then use a comparison operator == to test the condition that returned value Dayoftheweek is same with the index of the array Days and then print to a html document. The program may need improvements such as the fact that errors may arise when proper input isn't given, and therefore must be handled.